Guide To Challenging Gyms
This is a guide intended to, hopefully, make it a bit easier for people without much knowledge of Pokemon to understand how to earn a badge here at Route. It includes both general information, and analysis of each specific gym.
HOW TO EARN A BADGE
The official page on this is here on the mod journal, but here's a slightly more detailed explanation of the process.
You need mod approval for your character to earn a badge. Once you think they're ready, all you have to do is contact one of the mods (IMs and PMs are the fastest way). All you have to say is that your character is going to try a gym battle, and include a link to their Pokemon roster. If you have specific Pokemon or strategies you intend to use, you can also specify that.
You'll get a reply back once the mods determine how you character did in the battle. If they won, it'll just say that they won and you're free to make up the details yourself. If they lost, the mods will include an explanation of what went wrong (not leveled enough, too many Pokemon weak against the leader's attacks, etc).
You don't have to make a post for each gym battle, and even if you do you don't have to include the actual details of the battle -- your character can just be standing outside the gym with a badge, if you'd like. This is probably the easiest way to go about it if you aren't very familiar with Pokemon.
The rest of this is all about how to actually prepare for gym battles, and will hopefully help explain how to win them more easily.
HOW TYPES WORK IN BATTLE
This is a very brief and simplified overview of the mechanics of elemental types in Pokemon battles, for people who aren't familiar with them at all. If you already know how this works you can just skip to the next section.
Types are, essentially, a giant game of rock-paper-scissors, with 17 total types that can interact with each other. (Bulbapedia has a chart here showing all the interactions, if you're curious, but you don't need to know all of that.) If you use a type that's strong against your opponent's type in a battle, the attack does double damage -- for example, Water is strong against Fire, Fire is strong against Grass, and so forth. They're thus extremely important when it comes to battling.
The most important point to note is that both your Pokemon and each of their moves has a type. These are each used to determine something different in the battle, so it's important to know both.
When your Pokemon is attacking, determine the strength of your Pokemon's move type against the opponent's overall type. Example: Squirtle vs Charmander. Charmander's overall type is Fire, so if Squirtle uses Water Gun, a Water-type move, it will do double damage against Charmander, because Fire is weak to Water. However, if Squirtle uses Tackle, a Normal-type move, it will only do the standard amount of damage, because Fire is not weak to Normal.
Squirtle's overall type is in fact Water, but note that this is irrelevant to how much damage it does against Charmander. What's important is the type the move is.
When your Pokemon is defending, do the reverse -- determine the strength of your Pokemon's overall type against the opponent's move type. (Squirtle's type is Water, and Charmander only knows Fire- and Normal-type moves -- therefore, none of Charmander's attacks will do double damage to your Squirtle.)
Because of how this works, when you're comparing your lineup to the gym leader's, you need to make sure you're checking the correct types against each other. You need Pokemon whose overall types aren't weak to the gym leader's attacks, and whose move types are strong against the gym leader's overall types.
For the charts below, I've listed both the overall and move types that are most advantageous or disadvantageous against each gym leader's lineup.
GYM GUIDE
And finally, this part is about how to actually go about winning battles.
GENERAL TIPS
- Make sure your Pokemon's levels are about the same as the gym leader's, or higher. The higher your Pokemon's levels are, the less you have to worry about type matching at all. (If you're 20 levels above the gym leader, what kind of attack you're using really isn't going to matter too much.)
- You generally want around 3 solid Pokemon to use for at a gym -- they can be the same three for all the gyms, if you like. The more Pokemon you have at high levels, the less you have to worry about getting the type matching exactly right.
- Conversely, if your Pokemon's move types are very strong against the gym leader's overall types, you can get away with not being at quite as high levels. This won't do any good if your Pokemon are 10 levels below the gym leader's, however; they still have to be at around the same level.
- Note on TMs: If you don't have any Pokemon with the right move types, remember that you can buy TMs at the department store in Goldenrod. TMs teach your Pokemon a new move they couldn't otherwise learn, often a move of a different type than what it would normally learn. These can be very helpful for gym battles. However, note that each Pokemon can only learn certain TM moves. The TMs available for purchase are listed here, and to determine if your Pokemon can use a specific TM, check to see if it's on the list here (replace "Squirtle" in the URL with the name of the Pokemon you want to check).
For each gym I'll list the following:
- the leader's levels + recommended levels for your Pokemon
- the leader's Pokemon, their overall types, and their move types
- what moves you should and shouldn't use against each Pokemon
- what types of Pokemon you shouldn't use, based on the leader's move types
- overall strategies and notes on any specific difficulties for that gym
* Also, keep in mind that when I say you should do something or shouldn't do something, it doesn't mean that's the only way you can win a battle. So if you don't have a certain type of Pokemon I recommend, you can still win, you'll just have to adjust your strategy a bit, and maybe level your Pokemon a little more first. Everyone's team is different, so there's no one right way to do any of this.
VIOLET
FALKNER YOU Levels: 30-35 Levels: 35-45 NOCTOWL - Normal/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ghost, Ground Moves: Flying, Normal, Psychic TYPES
→ DON'T USE: Bug, Grass, Fighting, Poison HONCHKROW - Dark/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ground, Psychic Moves: Flying, Dark TYPES
→ DON'T USE: Bug, Grass, Fighting, Ghost, Psychic PIDGEOT - Normal/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ghost, Ground Moves: Flying, Normal TYPES
→ DON'T USE: Bug, Grass, Fighting OVERALL: Falkner specializes in Flying-types, so do not use Bug, Grass, or Fighting Pokemon at this gym, as they're all weak to Flying. His Pokemon are all weak to Electric, Ice, and Rock type moves, so get a couple of those and you'll be set. Make sure not to use any Pokemon that rely on Ghost or Ground type moves, as his Pokemon are all immune to those.
NOTES: The only potential snag here is the Honchkrow -- it uses Dark-type moves, so make sure to use at least one Pokemon that isn't Ghost or Psychic, because it'll destroy those. Also note that it's immune to Psychic-type moves.
AZALEA
BUGSY YOU Levels: 35-40 Levels: 40-50 PINSIR - Bug MOVES
→ USE: Fire, Flying, Rock
→ DON'T USE: --- Moves: Bug, Fighting, Normal TYPES
→ DON'T USE: Grass, Poison, Psychic, Normal, Rock, Steel, Ice, Dark HERACROSS - Bug/Fighting MOVES
→ USE: Fire, Flying, Psychic
→ DON'T USE: --- Moves: Normal, Flying, Fighting TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Bug, Fighting, Grass SCIZOR - Bug/Steel MOVES
→ USE: Fire
→ DON'T USE: Poison Moves: Normal, Steel, Bug, Dark TYPES
→ DON'T USE: Grass, Poison, Psychic, Ice, Rock, Ghost, Psychic OVERALL: This looks harder than it is. You should mostly avoid using Grass and Psychic types due to the Bug-type moves, and also Normal, Rock, Steel, Ice, and Dark types because of his two Pokemon that use Fighting moves. The key here is to have a Pokemon with strong Fire-type moves -- those can easily take out his entire team in a few hits, so his Pokemon won't have time to hurt yours too much, even if they are weak to his attacks.
NOTES: You really, really need some Fire-type moves for that Scizor. Flying-types will work just as well for his other two Pokemon, particularly Heracross, so it's good to have some of those moves around as well.
GOLDENROD
WHITNEY YOU Levels: 40-45 Levels: 45-55 GIRAFARIG - Normal/Psychic MOVES
→ USE: Bug, Dark
→ DON'T USE: Ghost Moves: Normal, Psychic, Dark TYPES
→ DON'T USE: Fighting, Poison, Ghost, Psychic CLEFABLE - Normal MOVES
→ USE: Fighting
→ DON'T USE: Ghost Moves: Normal, Fighting TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark MILTANK - Normal MOVES
→ USE: Fighting
→ DON'T USE: Ghost Moves: Normal, Rock, Psychic TYPES
→ DON'T USE: Bug, Fire, Flying, Ice, Fighting, Poison OVERALL: Her Pokemon aren't too dangerous, but the battle will be vastly easier if you can get a Pokemon with some good Fighting-type moves. (Note that there aren't any Fighting-type TMs available, so you'd need a Pokemon that learns them by leveling.) If you don't have any Fighting moves, it would probably be wise to get your Pokemon up a few extra levels before you try this gym. (At least around level 50, I'd say.) Also, while all of her Pokemon are immune to Ghost-type moves, a Ghost Pokemon with non-Ghost moves can be potentially very useful here, since Ghosts are immune to Normal and Fighting attacks.
NOTES: The Miltank is evil, and you want to be able to beat it as quickly as possible, which is why Fighting moves are highly recommended. Otherwise the battle can be tricky to win. You'll also need a non-Fighting Pokemon to use on the Girafarig; anything that learns Bite should work fine.
ECRUTEAK
MORTY YOU Levels: 45-50 Levels: 50-60 HAUNTER - Ghost/Poison MOVES
→ USE: Dark, Ghost, Psychic
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison MISDREAVUS - Ghost MOVES
→ USE: Dark, Ghost
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison GENGAR - Ghost/Poison MOVES
→ USE: Dark, Ghost, Psychic
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison OVERALL: This is the battle where you bring out your Dark-type moves -- if you have a few of those, it shouldn't be hard at all. Using Ghost Pokemon here is a double-edged sword; Ghosts are weak to Ghost moves, so while you can do some good damage to his Pokemon with them, his Pokemon can also do good damage to you, so just keep that in mind. Dark/Ghost types like Sableye aren't weak to Ghost moves, however, so one of those will be extremely effective in this fight. Otherwise, just make sure not to use any Pokemon that rely solely on Normal, Fighting, or Ground attacks, as his Pokemon are all immune to those.
NOTES: His Pokemon are all fairly similar, so this is pretty straightforward. There shouldn't be any particular snags.
CIANWOOD
CHUCK YOU Levels: 50-55 Levels: 55-65 HITMONLEE - Fighting MOVES
→ USE: Flying, Psychic
→ DON'T USE: --- Moves: Fighting, Fire TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Bug, Grass HITMONCHAN - Fighting MOVES
→ USE: Flying, Psychic
→ DON'T USE: --- Moves: Fighting, Normal, Steel, Electric, Ice, Fire TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Flying, Water, Dragon, Ground, Bug, Grass POLIWRATH - Water/Fighting MOVES
→ USE: Flying, Psychic, Grass, Electric
→ DON'T USE: --- Moves: Fighting, Water, Normal TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Fire, Ground OVERALL: You want Flying and Psychic moves here, which luckily aren't too hard to get. Don't use Normal, Rock, Steel, Ice, or Dark types if you can, since they're all weak to Fighting, and most of what you're going to be hit with is Fighting moves. Ghost Pokemon can do thus do well here, since Fighting moves can't hit them. His Pokemon hit hard, so a few extra levels might be helpful as well.
NOTES: The Hitmonchan can be a pain since it knows so many different types of attacks. Don't worry so much about your Pokemon's overall type for that one, and just use one with attacks that can defeat it quickly. If you have one, you can also bring along a Pokemon with some good Electric or Grass moves to handle the Poliwrath.
OLIVINE
JASMINE YOU Levels: 55-60 Levels: 60-70 SKARMORY - Steel/Flying MOVES
→ USE: Fire, Electric
→ DON'T USE: Poison, Ground Moves: Steel, Flying, Normal TYPES
→ DON'T USE: Ice, Rock, Bug, Fighting, Grass MAGNETON - Electric/Steel MOVES
→ USE: Fire, Ground, Fighting
→ DON'T USE: Poison Moves: Steel, Electric TYPES
→ DON'T USE: Ice, Rock, Flying, Water STEELIX - Steel/Ground MOVES
→ USE: Fire, Ground, Fighting, Water
→ DON'T USE: Poison, Electric Moves: Steel, Rock, Normal, Dragon, Dark TYPES
→ DON'T USE: Ice, Rock, Bug, Fire, Flying, Dragon, Ghost, Psychic OVERALL: Steel Pokemon are a pain in the ass due to their high defense, so using the right types of moves is particularly important here. Fire-type moves work the best, though Ground and Fighting moves will also be helpful. Don't bring Ice or Rock Pokemon, as they're weak to Steel, and be careful what you use against the Steelix.
NOTES: The Steelix can do a lot of damage to Fire Pokemon, so it's wise to bring along something else as well -- say a Water type to exploit Steelix's other weakness. You'll definitely want Pokemon of several different types here, since her Pokemon can all use different kinds of attacks.
MAHOGANY
PRYCE YOU Levels: 60-65 Levels: 65-75 DEWGONG - Water/Ice MOVES
→ USE: Fighting, Rock, Electric, Grass
→ DON'T USE: --- Moves: Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Fire, Rock LAPRAS - Water/Ice MOVES
→ USE: Fighting, Rock, Electric, Grass
→ DON'T USE: --- Moves: Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Fire, Rock MAMOSWINE - Ice/Ground MOVES
→ USE: Fighting, Steel, Fire, Water, Grass
→ DON'T USE: Electric Moves: Ice, Ground, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Electric, Fire, Poison, Rock, Steel OVERALL: Fighting-type moves will work on all of his Pokemon, but if you don't have any, you can still get by just fine with a combination of Electric and Water moves. Grass moves are strong against all of his Pokemon, but since Grass is weak against Ice, you don't want to bring your Grass Pokemon here. Don't bring Dragon, Flying, Ground, Fire, or Rock Pokemon, either.
NOTES: The Mamoswine is the tricky part here. Even though it's weak to Fire and Steel as well, it also has attacks that are strong against those two types, so be careful what Pokemon you use there. This is why I say to use Water -- it's the safest type to use against it. (If you have a Pokemon that isn't a Fire or Steel type but has Fire or Steel attacks, though, that would also work.) Also keep in mind that Mamoswine is immune to Electric moves, and has attacks strong against Electric Pokemon.
BLACKTHORN
CLAIR YOU Levels: 65-70 Levels: 70-80 GYARADOS - Water/Flying MOVES
→ USE: Electric, Rock
→ DON'T USE: Ground Moves: Dragon, Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock, Flying, Grass KINGDRA - Water/Dragon MOVES
→ USE: Dragon
→ DON'T USE: --- Moves: Dragon, Water TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock DRAGONITE - Dragon/Flying MOVES
→ USE: Dragon, Ice, Rock
→ DON'T USE: Ground Moves: Dragon, Water, Normal, Flying TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock, Bug, Fighting, Grass OVERALL: Dragons are another double-edged sword, in that they're weak to other Dragons. So if you happen to have any Dragon Pokemon, this is a good place to use them, just remember that her Pokemon can do a lot of damage to them as well. A Pokemon with Dragon-type moves that isn't a Dragon Pokemon will work better. (Though unfortunately there aren't any TMs with Dragon moves available.) Something with good Rock moves will also be helpful, though make sure it isn't an actual Rock Pokemon, since all of her Pokemon have strong Water attacks. Don't bring Fire or Ground Pokemon, either, for the same reason. Her Pokemon all have very strong attacks, so make sure you have several Pokemon at a high level and are well-prepared before you challenge this gym.
NOTES: Gyarados actually isn't a Dragon type, and it takes quadruple damage from Electric attacks, so the simplest way to defeat it is just to bring a Pokemon with those. Dragonite, meanwhile, takes quadruple damage from Ice attacks, so those are your best bet there. The Kingdra is only weak to Dragon attacks, so you can't use type advantages if you don't have any of those, but it also doesn't have a lot of different types of attacks, so you can always just get a strong Pokemon that isn't weak to its attacks and defeat it without a type advantage. If you're not sure you can defeat it, level up your Pokemon some more first.
If any part of this is confusing or if there's something you still have a question about, please let me know and I'll do my best to clarify!
HOW TO EARN A BADGE
The official page on this is here on the mod journal, but here's a slightly more detailed explanation of the process.
You need mod approval for your character to earn a badge. Once you think they're ready, all you have to do is contact one of the mods (IMs and PMs are the fastest way). All you have to say is that your character is going to try a gym battle, and include a link to their Pokemon roster. If you have specific Pokemon or strategies you intend to use, you can also specify that.
You'll get a reply back once the mods determine how you character did in the battle. If they won, it'll just say that they won and you're free to make up the details yourself. If they lost, the mods will include an explanation of what went wrong (not leveled enough, too many Pokemon weak against the leader's attacks, etc).
You don't have to make a post for each gym battle, and even if you do you don't have to include the actual details of the battle -- your character can just be standing outside the gym with a badge, if you'd like. This is probably the easiest way to go about it if you aren't very familiar with Pokemon.
The rest of this is all about how to actually prepare for gym battles, and will hopefully help explain how to win them more easily.
HOW TYPES WORK IN BATTLE
This is a very brief and simplified overview of the mechanics of elemental types in Pokemon battles, for people who aren't familiar with them at all. If you already know how this works you can just skip to the next section.
Types are, essentially, a giant game of rock-paper-scissors, with 17 total types that can interact with each other. (Bulbapedia has a chart here showing all the interactions, if you're curious, but you don't need to know all of that.) If you use a type that's strong against your opponent's type in a battle, the attack does double damage -- for example, Water is strong against Fire, Fire is strong against Grass, and so forth. They're thus extremely important when it comes to battling.
The most important point to note is that both your Pokemon and each of their moves has a type. These are each used to determine something different in the battle, so it's important to know both.
When your Pokemon is attacking, determine the strength of your Pokemon's move type against the opponent's overall type. Example: Squirtle vs Charmander. Charmander's overall type is Fire, so if Squirtle uses Water Gun, a Water-type move, it will do double damage against Charmander, because Fire is weak to Water. However, if Squirtle uses Tackle, a Normal-type move, it will only do the standard amount of damage, because Fire is not weak to Normal.
Squirtle's overall type is in fact Water, but note that this is irrelevant to how much damage it does against Charmander. What's important is the type the move is.
When your Pokemon is defending, do the reverse -- determine the strength of your Pokemon's overall type against the opponent's move type. (Squirtle's type is Water, and Charmander only knows Fire- and Normal-type moves -- therefore, none of Charmander's attacks will do double damage to your Squirtle.)
Because of how this works, when you're comparing your lineup to the gym leader's, you need to make sure you're checking the correct types against each other. You need Pokemon whose overall types aren't weak to the gym leader's attacks, and whose move types are strong against the gym leader's overall types.
For the charts below, I've listed both the overall and move types that are most advantageous or disadvantageous against each gym leader's lineup.
GYM GUIDE
And finally, this part is about how to actually go about winning battles.
GENERAL TIPS
- Make sure your Pokemon's levels are about the same as the gym leader's, or higher. The higher your Pokemon's levels are, the less you have to worry about type matching at all. (If you're 20 levels above the gym leader, what kind of attack you're using really isn't going to matter too much.)
- You generally want around 3 solid Pokemon to use for at a gym -- they can be the same three for all the gyms, if you like. The more Pokemon you have at high levels, the less you have to worry about getting the type matching exactly right.
- Conversely, if your Pokemon's move types are very strong against the gym leader's overall types, you can get away with not being at quite as high levels. This won't do any good if your Pokemon are 10 levels below the gym leader's, however; they still have to be at around the same level.
- Note on TMs: If you don't have any Pokemon with the right move types, remember that you can buy TMs at the department store in Goldenrod. TMs teach your Pokemon a new move they couldn't otherwise learn, often a move of a different type than what it would normally learn. These can be very helpful for gym battles. However, note that each Pokemon can only learn certain TM moves. The TMs available for purchase are listed here, and to determine if your Pokemon can use a specific TM, check to see if it's on the list here (replace "Squirtle" in the URL with the name of the Pokemon you want to check).
For each gym I'll list the following:
- the leader's levels + recommended levels for your Pokemon
- the leader's Pokemon, their overall types, and their move types
- what moves you should and shouldn't use against each Pokemon
- what types of Pokemon you shouldn't use, based on the leader's move types
- overall strategies and notes on any specific difficulties for that gym
* Also, keep in mind that when I say you should do something or shouldn't do something, it doesn't mean that's the only way you can win a battle. So if you don't have a certain type of Pokemon I recommend, you can still win, you'll just have to adjust your strategy a bit, and maybe level your Pokemon a little more first. Everyone's team is different, so there's no one right way to do any of this.
VIOLET
FALKNER YOU Levels: 30-35 Levels: 35-45 NOCTOWL - Normal/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ghost, Ground Moves: Flying, Normal, Psychic TYPES
→ DON'T USE: Bug, Grass, Fighting, Poison HONCHKROW - Dark/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ground, Psychic Moves: Flying, Dark TYPES
→ DON'T USE: Bug, Grass, Fighting, Ghost, Psychic PIDGEOT - Normal/Flying MOVES
→ USE: Electric, Ice, Rock
→ DON'T USE: Ghost, Ground Moves: Flying, Normal TYPES
→ DON'T USE: Bug, Grass, Fighting OVERALL: Falkner specializes in Flying-types, so do not use Bug, Grass, or Fighting Pokemon at this gym, as they're all weak to Flying. His Pokemon are all weak to Electric, Ice, and Rock type moves, so get a couple of those and you'll be set. Make sure not to use any Pokemon that rely on Ghost or Ground type moves, as his Pokemon are all immune to those.
NOTES: The only potential snag here is the Honchkrow -- it uses Dark-type moves, so make sure to use at least one Pokemon that isn't Ghost or Psychic, because it'll destroy those. Also note that it's immune to Psychic-type moves.
AZALEA
BUGSY YOU Levels: 35-40 Levels: 40-50 PINSIR - Bug MOVES
→ USE: Fire, Flying, Rock
→ DON'T USE: --- Moves: Bug, Fighting, Normal TYPES
→ DON'T USE: Grass, Poison, Psychic, Normal, Rock, Steel, Ice, Dark HERACROSS - Bug/Fighting MOVES
→ USE: Fire, Flying, Psychic
→ DON'T USE: --- Moves: Normal, Flying, Fighting TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Bug, Fighting, Grass SCIZOR - Bug/Steel MOVES
→ USE: Fire
→ DON'T USE: Poison Moves: Normal, Steel, Bug, Dark TYPES
→ DON'T USE: Grass, Poison, Psychic, Ice, Rock, Ghost, Psychic OVERALL: This looks harder than it is. You should mostly avoid using Grass and Psychic types due to the Bug-type moves, and also Normal, Rock, Steel, Ice, and Dark types because of his two Pokemon that use Fighting moves. The key here is to have a Pokemon with strong Fire-type moves -- those can easily take out his entire team in a few hits, so his Pokemon won't have time to hurt yours too much, even if they are weak to his attacks.
NOTES: You really, really need some Fire-type moves for that Scizor. Flying-types will work just as well for his other two Pokemon, particularly Heracross, so it's good to have some of those moves around as well.
GOLDENROD
WHITNEY YOU Levels: 40-45 Levels: 45-55 GIRAFARIG - Normal/Psychic MOVES
→ USE: Bug, Dark
→ DON'T USE: Ghost Moves: Normal, Psychic, Dark TYPES
→ DON'T USE: Fighting, Poison, Ghost, Psychic CLEFABLE - Normal MOVES
→ USE: Fighting
→ DON'T USE: Ghost Moves: Normal, Fighting TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark MILTANK - Normal MOVES
→ USE: Fighting
→ DON'T USE: Ghost Moves: Normal, Rock, Psychic TYPES
→ DON'T USE: Bug, Fire, Flying, Ice, Fighting, Poison OVERALL: Her Pokemon aren't too dangerous, but the battle will be vastly easier if you can get a Pokemon with some good Fighting-type moves. (Note that there aren't any Fighting-type TMs available, so you'd need a Pokemon that learns them by leveling.) If you don't have any Fighting moves, it would probably be wise to get your Pokemon up a few extra levels before you try this gym. (At least around level 50, I'd say.) Also, while all of her Pokemon are immune to Ghost-type moves, a Ghost Pokemon with non-Ghost moves can be potentially very useful here, since Ghosts are immune to Normal and Fighting attacks.
NOTES: The Miltank is evil, and you want to be able to beat it as quickly as possible, which is why Fighting moves are highly recommended. Otherwise the battle can be tricky to win. You'll also need a non-Fighting Pokemon to use on the Girafarig; anything that learns Bite should work fine.
ECRUTEAK
MORTY YOU Levels: 45-50 Levels: 50-60 HAUNTER - Ghost/Poison MOVES
→ USE: Dark, Ghost, Psychic
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison MISDREAVUS - Ghost MOVES
→ USE: Dark, Ghost
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison GENGAR - Ghost/Poison MOVES
→ USE: Dark, Ghost, Psychic
→ DON'T USE: Normal, Fighting, Ground Moves: Ghost, Dark, Psychic TYPES
→ DON'T USE: Ghost, Psychic, Fighting, Poison OVERALL: This is the battle where you bring out your Dark-type moves -- if you have a few of those, it shouldn't be hard at all. Using Ghost Pokemon here is a double-edged sword; Ghosts are weak to Ghost moves, so while you can do some good damage to his Pokemon with them, his Pokemon can also do good damage to you, so just keep that in mind. Dark/Ghost types like Sableye aren't weak to Ghost moves, however, so one of those will be extremely effective in this fight. Otherwise, just make sure not to use any Pokemon that rely solely on Normal, Fighting, or Ground attacks, as his Pokemon are all immune to those.
NOTES: His Pokemon are all fairly similar, so this is pretty straightforward. There shouldn't be any particular snags.
CIANWOOD
CHUCK YOU Levels: 50-55 Levels: 55-65 HITMONLEE - Fighting MOVES
→ USE: Flying, Psychic
→ DON'T USE: --- Moves: Fighting, Fire TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Bug, Grass HITMONCHAN - Fighting MOVES
→ USE: Flying, Psychic
→ DON'T USE: --- Moves: Fighting, Normal, Steel, Electric, Ice, Fire TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Flying, Water, Dragon, Ground, Bug, Grass POLIWRATH - Water/Fighting MOVES
→ USE: Flying, Psychic, Grass, Electric
→ DON'T USE: --- Moves: Fighting, Water, Normal TYPES
→ DON'T USE: Normal, Rock, Steel, Ice, Dark, Fire, Ground OVERALL: You want Flying and Psychic moves here, which luckily aren't too hard to get. Don't use Normal, Rock, Steel, Ice, or Dark types if you can, since they're all weak to Fighting, and most of what you're going to be hit with is Fighting moves. Ghost Pokemon can do thus do well here, since Fighting moves can't hit them. His Pokemon hit hard, so a few extra levels might be helpful as well.
NOTES: The Hitmonchan can be a pain since it knows so many different types of attacks. Don't worry so much about your Pokemon's overall type for that one, and just use one with attacks that can defeat it quickly. If you have one, you can also bring along a Pokemon with some good Electric or Grass moves to handle the Poliwrath.
OLIVINE
JASMINE YOU Levels: 55-60 Levels: 60-70 SKARMORY - Steel/Flying MOVES
→ USE: Fire, Electric
→ DON'T USE: Poison, Ground Moves: Steel, Flying, Normal TYPES
→ DON'T USE: Ice, Rock, Bug, Fighting, Grass MAGNETON - Electric/Steel MOVES
→ USE: Fire, Ground, Fighting
→ DON'T USE: Poison Moves: Steel, Electric TYPES
→ DON'T USE: Ice, Rock, Flying, Water STEELIX - Steel/Ground MOVES
→ USE: Fire, Ground, Fighting, Water
→ DON'T USE: Poison, Electric Moves: Steel, Rock, Normal, Dragon, Dark TYPES
→ DON'T USE: Ice, Rock, Bug, Fire, Flying, Dragon, Ghost, Psychic OVERALL: Steel Pokemon are a pain in the ass due to their high defense, so using the right types of moves is particularly important here. Fire-type moves work the best, though Ground and Fighting moves will also be helpful. Don't bring Ice or Rock Pokemon, as they're weak to Steel, and be careful what you use against the Steelix.
NOTES: The Steelix can do a lot of damage to Fire Pokemon, so it's wise to bring along something else as well -- say a Water type to exploit Steelix's other weakness. You'll definitely want Pokemon of several different types here, since her Pokemon can all use different kinds of attacks.
MAHOGANY
PRYCE YOU Levels: 60-65 Levels: 65-75 DEWGONG - Water/Ice MOVES
→ USE: Fighting, Rock, Electric, Grass
→ DON'T USE: --- Moves: Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Fire, Rock LAPRAS - Water/Ice MOVES
→ USE: Fighting, Rock, Electric, Grass
→ DON'T USE: --- Moves: Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Fire, Rock MAMOSWINE - Ice/Ground MOVES
→ USE: Fighting, Steel, Fire, Water, Grass
→ DON'T USE: Electric Moves: Ice, Ground, Normal TYPES
→ DON'T USE: Dragon, Flying, Grass, Ground, Electric, Fire, Poison, Rock, Steel OVERALL: Fighting-type moves will work on all of his Pokemon, but if you don't have any, you can still get by just fine with a combination of Electric and Water moves. Grass moves are strong against all of his Pokemon, but since Grass is weak against Ice, you don't want to bring your Grass Pokemon here. Don't bring Dragon, Flying, Ground, Fire, or Rock Pokemon, either.
NOTES: The Mamoswine is the tricky part here. Even though it's weak to Fire and Steel as well, it also has attacks that are strong against those two types, so be careful what Pokemon you use there. This is why I say to use Water -- it's the safest type to use against it. (If you have a Pokemon that isn't a Fire or Steel type but has Fire or Steel attacks, though, that would also work.) Also keep in mind that Mamoswine is immune to Electric moves, and has attacks strong against Electric Pokemon.
BLACKTHORN
CLAIR YOU Levels: 65-70 Levels: 70-80 GYARADOS - Water/Flying MOVES
→ USE: Electric, Rock
→ DON'T USE: Ground Moves: Dragon, Ice, Water, Normal TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock, Flying, Grass KINGDRA - Water/Dragon MOVES
→ USE: Dragon
→ DON'T USE: --- Moves: Dragon, Water TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock DRAGONITE - Dragon/Flying MOVES
→ USE: Dragon, Ice, Rock
→ DON'T USE: Ground Moves: Dragon, Water, Normal, Flying TYPES
→ DON'T USE: Dragon, Fire, Ground, Rock, Bug, Fighting, Grass OVERALL: Dragons are another double-edged sword, in that they're weak to other Dragons. So if you happen to have any Dragon Pokemon, this is a good place to use them, just remember that her Pokemon can do a lot of damage to them as well. A Pokemon with Dragon-type moves that isn't a Dragon Pokemon will work better. (Though unfortunately there aren't any TMs with Dragon moves available.) Something with good Rock moves will also be helpful, though make sure it isn't an actual Rock Pokemon, since all of her Pokemon have strong Water attacks. Don't bring Fire or Ground Pokemon, either, for the same reason. Her Pokemon all have very strong attacks, so make sure you have several Pokemon at a high level and are well-prepared before you challenge this gym.
NOTES: Gyarados actually isn't a Dragon type, and it takes quadruple damage from Electric attacks, so the simplest way to defeat it is just to bring a Pokemon with those. Dragonite, meanwhile, takes quadruple damage from Ice attacks, so those are your best bet there. The Kingdra is only weak to Dragon attacks, so you can't use type advantages if you don't have any of those, but it also doesn't have a lot of different types of attacks, so you can always just get a strong Pokemon that isn't weak to its attacks and defeat it without a type advantage. If you're not sure you can defeat it, level up your Pokemon some more first.
If any part of this is confusing or if there's something you still have a question about, please let me know and I'll do my best to clarify!