Dawn was born ten years prior to the series, in a small little town called Twinleaf Town in the Sinnoh region. Her mother is Johanna, who was a famous coordinator in the Sinnoh region at that time; in fact, she had the title of "Top Coordinator".
Most of Dawn's life until she was seven is unknown, though it is safe to assume that she was either being babysat by someone (due to Johanna traveling around for contests) or was being taken care at home.
When she was seven, Dawn went to a Pokémon Kindergarten. She was bullied a lot there, but got help from her childhood friend, Leona. Her other childhood friend, Kenny was interested in contests; which is why they became friends in the first place. However, due to an incident when Dawn was squishing the Kindergarten's Minun and Plusle, she got shocked -- which made her hair sparkle. She then got the nickname "Dee-Dee" because her hair was Diamond Dusted.
Two to three years later (it doesn't state how old she was when she was in kindergarten, I'm assuming she was around 6-7 years old), when she turned ten -- or was close to turning eleven, again, this is not stated, but is my basic headcanon based on what it says Ash's birthday is -- she started her journey to become a Top Coordinator herself, just like her mother was, long ago (Johanna had long retired from doing contests, though ).
In the beginning of Dawn's journey, she talks about her plans on becoming a Coordinator, and she also daydreams about which starter Pokémon to choose; Piplup (the water-type), Chimchar (the fire-type), and Turtwig (the grass-type). I might as well note here that Ash did the same thing in the beginning of his journey, but that's not too important. Dawn then decides to head to Professor Rowan's place -- which she had directions to from a postcard that she had been given via mail; so she decides to go to Sandgem Town; even if she doesn't know exactly what Pokémon she will get just yet.
On bike, she soon attempt to head to Sandgem Town, and she does arrive at the town -- only to figure out that she has no clue how to read the map and find out how to get to the Professor's lab. That is, until she bumps into the Professor himself, who then leads her to his lab. But there's one problem. All the starter Pokémon are in a fight! And because both Chimchar and Piplup ran off, Dawn asks if she could go and find them, and the Professor says that it's alright.
So! Dawn goes off to save the two Pokémon!! She then goes off in order to attempt finding the Piplup and Chimchar -- which are the two Pokémon that might be her future partner. But they're still fighting -- until she finds Piplup stuck in an Ariados' web, where she soon has a good idea on how to free Piplup out of the web, which was for it to attack the web. Even though she did save the water-penguin, the little guy was still angry and scared -- and the two of them didn't get along nicely, but then they got attacked by a whole group of Ariados and their webs. However, just when they were going to escape, Dawn gets captured by the Ariados -- but Piplup then protects Dawn by using Bide, and Dawn was glad that he helped. However, Piplup was quite injured.
While traveling back, Dawn finally heads to Lake Verity, where she sees a mysterious Pokémon -- Mesperit, to be exact. She then heads back to the lab, where she is to choose her first Pokémon. And who does she choose...? Piplup! She then puts it back in its Pokéball and heads on her way to start her journey!
They start on Route 202, and the two of them wonder what new Pokémon trainers do first -- and then she has finally decided. To catch some Pokémon. And so Dawn attempts to do so, but to no avail, due to the fact that she makes mistakes in the beginning. She then talks to her Piplup about Pokémon Contests and catching Pokémon! However, not only does Piplup makes a mistake, but Dawn makes mistakes as well. After all -- she knows that she's just a beginner! But soon enough, she sees... Ash's Pikachu! Of course, she thinks that Pikachu is a wild Pokémon. But when she tries to catch it, his Pikachu destroys Dawn's bike (by accident!!) but Pikachu does feel sorry about it... and so Dawn tries to catch it -- except she soon realizes that Pikachu belongs to someone. This is the same time where she meets Team Rocket, who she figures out that they are horrible people, and she then decides to help Pikachu out and protect it.
Pikachu is then very injured, so Dawn goes to the nearest Pokémon Center to make sure it will be alright. She then reports to her mother about Piplup and to the Professor to tell him about the trainer's Pikachu. And so she heads off to find Ash! And she's a bit upset about her crispy bike, which Pikachu ... feels sorry for, since the whole ordeal's a big problem.
Suddenly... Team Rocket strikes again! Dawn's pretty confused on why the trio keeps on trying to capture Pokémon the wrong way. So, she decides to fight Team Rocket. However, it's not working out so well, as the duo (Dawn and Piplup) are still new trainers... but then Ash comes to save the day!! And Dawn and Ash's first meeting is quite surprising, for she notices that he's not only a really good trainer, he's pretty crazy -- doing crazy enough to go and jump straight into a machine and even JUMP ONTO IT. And it's quite obvious that Dawn is... way surprised. And she probably couldn't do something like this even if she tried. Or at least, not as a starting trainer, anyway.
The machine blows up and Pikachu and Ash meet up again! And she finally introduces herself to both Ash and Brock and it seems that the three of them become friends right from the start. They head back to Professor Rowan's lab, where they talk to Professor Oak for a bit (Dawn only knows him by the Pokémon poetry he does on TV!!) And then Dawn's first encounter with Paul!! She's pretty excited, since this is the first time seeing an actual Pokémon battle. Which ends in a tie.
The three of them (Ash, Dawn and Brock) then finally decide to journey together as a group, and this is where the real journey begins.
Early in the series (EP004), Dawn's first rival (besides Kenny!!) was Nando, and in order to show her prowess to Ash, she decided to battle him... where she loses her first battle, though she knows there's nothing to worry about. She then hears from the local Nurse Joy that Nando is wondering which to choose, whether it be contests or gym battles-- which leads into an all-out fight between Dawn and Ash to show which is better, which is a huge conflict. But once they hear the song of the forest, the two of them soon realize that their conflict was for nothing. And once they find out that Nando is going to compete in both contests and gym battles and the whole problem is solved.
So far, I've talked about the first four episodes straight, so from here on out in the application, I will actually be skipping through and speaking only about important episodes that involve her growth.
In EP007, Dawn attempts to teach Piplup a new contest move, but it was only when Piplup came to help out some Pokémon in need is when Piplup is finally able to do that combination.
A few episodes later, in fact, EP009 shows that Dawn needs to catch more Pokémon -- and that's when she decides that she has to catch a Buneary!! Of course, Ash and Dawn end up having a fight over it because Buneary seems like an awesome Pokémon (it saved Pikachu, after all). And when Dawn helped save Buneary from Team Rocket, the two of them became friends (though Dawn wanted a proper fight in order to catch it...) and then -- she finally caught her very first Pokémon! And speaking of contests, it's time for everyone to head to Jubilife City!
Once in Jubilife City, it's quite obvious what's going to happen. That's right, folks -- a contest! And not only is Dawn going to enter in it, but Ash is too (since Aipom is amazing and wants to enter contests). Of course, she got her first contest outfit from her mother... and also met Zoey for the first time.
And when the contest started, she was quite nervous, due to the fact that she would be battling with impressive coordinators like Zoey and Ash as well! When she saw the two of them in action, they were pretty good, and that fact made Dawn even more nervous.
She soon goes to the semi-finals where she is able to battle Zoey, and the two of them end up in a heated battle -- not knowing who would win until the very end, until the very end, and the verdict is.... Zoey's the winner! But at least she gains a new friend. Even if she did lose, and she also learned a new lesson: not to call her mother every time Dawn won or lost a battle, but to rely on her friends. And her Pokémon.
The journey then continues, as Dawn and Ash catch new Pokémon, Dawn earns more ribbons and Ash earns more badges.
The third Pokémon that Dawn decides to capture is Pachirisu, an electric-type (just like Pikachu!!) because it it just adorable. The capture of Pachirisu was actually quite simple, and in fact -- it wasn't that hard for her to capture it.... easier than the ones she had caught in the past. However, Pachirisu was going to be quite difficult to tame, for it didn't listen to any of Dawn's commands and did whatever it wanted. So, Dawn decided to release it -- which is when Dawn realizes (later on, that is) that she made a huge mistake, Pachirisu and Dawn soon become good friends.
In EP022, Dawn enters a 'fake' contest where she has to battle against Ash's Aipom (being borrowed by Jessie!!) using her Pachirisu. She loses the battle, but she knows that the whole battle was pretty good practice for the next contest.
And soon enough, in DP026, Dawn and the gang meet up with Kenny, who tends to make fun of Dawn a lot by using her 'childhood stories', which annoyed Dawn. But the good thing about this whole shindig was that Piplup learned Whirlpool!
And the next day... the contest begins, time for the Floaroma contest!! With a new move in her arsenal, there's no need to worry, right? But in the first part of the contest, where Dawn uses Pachirisu, and it's quite obvious that she's in trouble when Pachirisu is not listening to Dawn at first, but she manages to have a magnificent turn around!
Dawn then manages to get into the final round of the contest, where she has to battle Kenny. It becomes a wonderful battle between Prinplup and Piplup -- and it ends with Dawn's win and she gets her first ribbon!
Skipping many filler episodes, it's time for Dawn to catch her next Pokémon! And in fact, it's a Buizel who's actually pretty tough. She doesn't catch it in her first attempt like everyone else (Zoey and Ash), but in her second try, she does manage to capture the water-type.
A few episodes later, due to the fact that Buizel seems more interested in Ash's gym battle training just like Ash's Aipom was interested in contests, which ended up in the two of them actually trading, even though they were quite worried about the whole ordeal, mostly because the two of them had already bonded with their Pokémon -- so they decide to do a practice battle! Dawn using Aipom and Ash using Buizel, and it works out perfectly, so, a trade it is!
However, before this, an evil team (other than Team Rocket) appears -- and that's Team Galactic! And because the whole Team Galactic plot gets really complicated, I'm just going to explain it here, even though it's pretty spoiler-y. Anyway, Team Galactic's plot was to get both the Adamant Orb and the Lustrous Orb and use the Red Chain to take control of both Palkia and Dialga in order to create a new world. Of course, they also had to use the three lake guardians' powers which gave Dawn a huge headache amongst the others. But she and the others managed to stop them and Pokémon Hunter J (who is an evil person who captures Pokémon, turns them to stone, and then just... gives it to whoever she is paying).
In the next contest, which is the Double Battle performance, Dawn decides to enter under Nando's suggestion. The first round, being the appeal round -- Dawn does pretty well, and everyone else seems to think so. However, when it comes to the judging, she actually doesn't pass the first round, and this ordeal actually upsets the coordinator, and everyone notices. And when Nando beats Zoey, Zoey decides to talk to Dawn and thus she gets less depressed. No need to worry, right?
The next contest is the Solaceon Town contest, and Dawn, once again, loses in the appeal round, which upsets her even more than before, which brings her down a lot, though she doesn't seem too confident on entering another contest, that's for sure. But she knows that you win some and then you lose some. But losing twice made her forget what was truly important about contests, which was the Pokémon!!
Now onto the Wallace Cup. Once again, Ash decides to enter with Buizel (since Buizel's never been in a contest) along with Dawn -- and look who decides to come to Sinnoh! That's right folks, it's Ash's friend from Hoenn, May! The two of them bond over contests, and they head to the restaurant, but it's no ordinary one.
In the Wallace Cup, Dawn's not that confident, but is soon reassured by May and Zoey that there's "no need to worry". She passes the whole appeal round with ease (though she was quite nervous still, especially when she saw all the others' appeals!!), and wins the contest by beating May in the final round.
Now it's time for Dawn to catch her fifth Pokémon!! Since she finally got her second ribbon, she finally regained her faith, and there's nothing to worry about. And that's when she decides to catch a Swinub (another cutie!!) though it's mostly due to the fact that it loves food. And now it's off to Celestic Town, the next contest!
Okay, so the Pokémon Collection is up next, and because Dawn was really talented when it came to designing, she actually won, and she is quite surprised. In the last episode of DP, Dawn's Buneary is actually scouted out to become a model for a Pokémon Stylist.
In DP095, Dawn and Brock bond over the Pokémon Stylist, Lila, and soon enough, the Celestic Town contest in underway!! However, Lila is also in the contest...which is going to be quite tough for Dawn. But the fight was quite difficult due to Lila's attacks, but she managed to pull it off and win her third ribbon!
Her next ribbon is then won in DP114, where she meets Ursula, who becomes her newest contest rival. Ursula finds Dawn quite annoying, just because she (Dawn) was the one who won the Wallace Cup, and thought that Dawn herself didn't deserve it. That is, until she actually sees Dawn in action.
A few episodes ago, when her Swinub evolved (in both its second and third forms), it began to disobey Dawn, much like Ash's Charizard did. But, in DP119, Dawn's Mamoswine finally begins to obey her. Of course, it's only after an Aggron tries to harm her and the mere fact that she's in huge trouble and Dawn helps its injury.
Okay, so it's DP122... and in Sandalstraw Town, Dawn notices that Piplup is starting to evolve. However, Piplup doesn't want to evolve... and it doesn't want to change. Even though Dawn seems excited about it, Piplup is rejecting the whole thing, which means that Dawn is actually not very understanding of Piplup's feelings. Piplup doesn't want to evolve, not now, not ever. However, Piplup is using too much energy using Bide, and Dawn doesn't understand why he doesn't want to go through the change. In the midst of all this, Team Rocket manages to kidnap Dawn's Piplup, Kenny's Prinplup, and Barry's Empoleon. This obviously makes Dawn angry with rage -- but when Meowth translates what Piplup says, being that Piplup didn't want to evolve because it wanted to help out Dawn the way it was, and because it did the same thing on day one, and that's when Dawn finally understands the reason why it was preventing its evolution in the first place. Once Dawn and the gang stop Team Rocket and save the day, they go back to the Pokémon Center to get an Ever Stone to prevent Piplup from ever evolving, and it's time for some training for the contest in Sandalstraw!
So, while Ash and Barry are practicing for the ping-pong match, Dawn is ready to go for the next contest, where she will be using Ambipom for both rounds! She decided to do this because Ambipom originally belonged to Ash and she wants to thank him for trading with her. After all, if she didn't have Ambipom today, she wouldn't have such a well-trained Pokémon by her side competing for her. She loses the ribbon to Kenny, but she's reminded that there's always next time! Barry, of course, noticed Ambipom's abilities in the contest (more so, Ambipom's ping-pong skills) and suggested to Dawn that maybe she should enter the ping-pong competition.
Dawn agrees, and decides to do so. However, she has no clue what Pokémon ping-pong is. After a short explanation from Barry, she decides that she should do her best! After all, Ambipom seems pretty pumped up about participating. Dawn manages to do the best out of the three of them, and Dawn notices that Ambipom even helped Dawn a lot when her paddle broke in her match... but she lost the match, but at least the two of them had a great time! In the Pokémon Center, O tells Dawn that he wants to scout out Dawn's Ambipom to become one of the best Pokémon Ping Pong players there is. Dawn is clearly upset by this. Does she really have to give up a Pokémon that she clearly bonded with...? She then goes to Ash for advice, since he was Ambipom's original trainer (when it was an Aipom), where she learns that she should let her Pokémon decide for themselves.
The following day, she asks Ambipom the big question. "What do you like more? Contests or ping-pong?" Of course, since she doesn't understand Pokéspeak, she uses representations of each sport, and Ambipom finally decides to follow its heart and become a Ping Pong Master!! So, this is finally good-bye for now, but Dawn knows she did what was right for her Pokémon...
And so they continue on with their journey.
Next up is the Twinleaf Festival, where Dawn introduces Ash and Brock to her home -- Twinleaf Town! Here, Dawn asks her own mother to a practice double-battle, which she loses, though she did pretty well. After all, her mother is a Top Coordinator, who has only lost once in her whole life as a coordinator.
During the Twinleaf Festival, Barry, Dawn, and Ash finding a magical circus tent that allowed the three of them to relive the precious moments in their lives -- miniaturized! Dawn gets to relive the first time she met Piplup, and boy, was it a big encounter.
After the Twinleaf Festival, it's time to head on out to the next town, where they end up bumping into Lyra, a young and aspiring trainer from Johto who is actually helping out in another festival, that's right, the Johto festival! Lyra makes fun of Dawn (and even ships Ash/Dawn), and calls her nicknames, but to be honest, it isn't as bad as Dee-Dee, really.
On the day of the Lilypad Contest, Dawn is ready to roll. She's going to use Mamoswine in the battle portion, and this is actually her first time using it in a contest. However, due to the fact that Mamoswine got really angry during the final round that it got out of control, making Dawn lose. Lyra was pretty shocked, yes, but Dawn told her that it was okay. Besides, she'll just win the next one!
After the whole festival season was over, it's time for another contest! In DP161, Dawn decides to enter herself in the Daybreak Contest, which is, yet again, another tag battle contest. She's quite determined to win this time -- however, Ursula, her contest rival shows up with... that's right, Minun and Plusle! And the problem with that is one thing: Dawn is completely terrified of them!! However, when she tells Ash and Dawn how she got the nickname Dee-Dee and why she was so scared of the two electric mice, she was then told that it was only because she had squeezed them too hard. Dawn realizes that it must have been something like that, and then decides that it will be alright.
During the contest, Dawn makes it to the battle round, and the finals... against Ursula! This is when she has to face her fear and beat back the Minun and Plusle and therefore, get over it. She manages to beat Ursula and get her final ribbon!!
In DP167, Dawn and co. are going to head to the Valor Lakefront for the Grand Festival, but are stopped by Johanna, who asks the gang if they could help out a Pokémon Coordinator school because she (Johanna) is filling in for Nurse Joy in the next contest in Neighborly Town. During this whole thing, she manages to teach the kids a lot of new things -- as well as perfect her Ice Chandelier!
Four episodes later, Dawn meets her doppelgänger, Princess Salvia -- who decides to ask Dawn to switch places with her so she could enter in the contest. Of course, Dawn agrees, but figures out that being a princess is a lot harder than it looks. Though, in return for allowing the Princess to enter the contest, she lends Dawn her Togekiss, so that it may be in more contests to come (especially the Grand Festival).
And finally... it's time for the Grand Festival to begin!! On the day before the festival begins, the gang goes to the coordinator meet and greet and they hang out together before the Grand Festival begins the next day.
The first stage is a double performance, and as Dawn watches all her opponents' performances, she notices that everyone has improved so much, and they all are really good. This, obviously, makes Dawn quite nervous, though she knows that there's no need to worry. Then, it's finally Dawn's turn! She decides to use Buneary and Cyndaquil in her appeal, and she pulled it off! And the results of the first round are that Dawn, Nando, Ursula, Zoey, and Jessilina (Jessie) move on to the second round, while Kenny gets kicked out of the Grand Festival. Kenny then wishes Dawn good luck ... and the second round begins the next day!!
And in round two, Dawn goes up against Ursula, and she knows it's not going to be easy. She decides to use Pachirisu and Mamoswine while Ursula uses Gabite and Flareon. As the battle goes on, Dawn begins to lose a whole bunch of points, but Dawn manages to pull through using Ice Chandelier as her basis -- and due to a K.O. from Ursula, she passes the round! Onto the next round.
The rounds continue and Dawn wins over and over until she goes to the semi-finals, where she has to battle Jessilina, but Dawn manages to win this battle with ease, where she gets to battle Zoey!!
She decides to use Togekiss and Piplup, while Zoey goes and uses Gallade and Glameow -- and in the heated battle, Dawn had to catch up to Zoey, who had made Dawn lose a lot of points in the first half, but even though they were neck to neck, Zoey still won in the end, winning the title of Top Coordinator. At the end, Dawn gives back the ribbon to her mother, since she no longer needs it, and she has the five ribbons that she won and her friends.
Dawn then speaks to Zoey, congratulating her on being a Top Coordinator. Zoey then asks Dawn if she wants to come with her to Snowpoint to party, but Dawn declines, saying that she still has to cheer for Ash in the Sinnoh League. She then tells her Pokémon that there's nothing to worry about, because it's all a part of the journey...
And the dream, which continues on.
In DP180, Kenny tells Dawn, "If I challenge Ash to a battle and win, you gotta go on a journey with me!" But all Dawn can think about at this point is cheering on Ash, but she has no clue what to do after the Sinnoh League. When she sees Ash lose, Dawn is kind of surprised (and a bit upset!!). And that's when Kenny indirectly confesses his love for Dawn. She then gives Kenny a letter, saying that she will continue her journey with Ash, but as long as they have the same dream, the two of them will meet again.
Then.... Sinnoh League happens. Ash gets into the Top 4, and they go home after that. Once they arrive back in Twinleaf Town, they have a nice rest there, until it's time for Brock and Ash to leave for Kanto. Of course, Dawn wanted to go with Ash to the Kanto region, but due to Buneary being scouted out as a model, she had to stay in the Sinnoh region.
After the end of the series, Dawn goes to have the photo shoot for Buneary, and it ended up great! So, Dawn goes back home to have one huge problem - she doesn't know where to go, and which of her Pokémon to bring. So, she has a battle with her mother using Piplup and Cyndaquil. Which doesn't end up well since they fight. A lot. But who cares about that, it's not really important. Afterwards, Dawn heads to the Professor's Lab where she meets a girl - a new trainer - and the events play out just like the first episode of the series. With the exception that Dawn's helping out with her team and the fact that after getting kidnapped by Ariados, they manage to get out of the situation by what we call evolution. That's right. Cyndaquil evolves.
And that's when she decides. Let's go to Hoenn for contests. With everyone. And while she heads to Hoenn on a boat, it's time for a new adventure.