Mesmer the Kadabra ♂
Psychic
Catcher: Mutou Sugoroku
Item: TwistedSpoon
Mild nature.
Often naps.
Inner Focus
Teleport // Reflect
Psybeam // Kinesis
The oldest of the Mutou family's pokémon, Mesmer was found as an Abra by Sugoroku in the tomb of the Nameless Pharaoh. When the Mutou elder was shot near into a long drop by his raider partner, he saw an unknown figure above him, and moments later Mesmer appeared, and teleported him back to the surface - with a certain Puzzle.
Near forty years later would find Mesmer living quietly in the Mutou household, alongside a Swablu - White Wing - Sugoroku found on another expedition in an otherwise dead end of a tomb. White Wing was well received by Mrs. Mutou, passing as a rare parrot and helping with the cleaning and singing Yuumi to sleep, while Mesmer slept most the day away, and randomly teleported around the house, amusing Yuumi but giving lots of scares of discovery.
Life changed big time when Setsuna blackmailed Sugoroku into battling her with White Wing. She won the pokémon from him when he surrendered, then used her newly made pokéballs to control White Wing, as she did with her own two Swablus. To avenge the move and convince the CEO to leave them be, Yuumi went through Setsuna's deadly amusement park with her friends. Hiro, who fell out of the run halfway through and was saved by Mokuba, brought Mesmer from the Mutous just before she was to face Setsuna. So Yuumi - or the spirit in Yuumi - used the Puzzle to guide Mesmer in a battle. She was at a clear disadvantage, but the now trio of Swablus were tired from their earlier fight, and be it from latent experience or the influence of the Puzzle Abra evolved into Kadabra, and won the fight.
Setsuna had bet a Dratini on the battle rather than White Wing, claiming the Swablu wasn't a fair bet against an Abra. Yuumi accepted the terms and trusted the won Dratini to Katsumi, gifting her her first pokémon. But Mesmer wasn't to stay Yuumi's only pokémon for long, as he went with her to Pegasus's Island to save Sugoroku, coming along as a loose pokémon at her side. There Mesmer helped Yuumi capture her first wild pokémon - a Diglett, Aerodactyl, and Tirtouga she named Goomba, Crag, & Blast respectively - and fought for the granddaughter against many people, like Inspector Haga, Paradox Brothers, and finally Pegasus himself. It was when Yuumi saved Sugoroku that he officially passed Mesmer on to her, and the Kadabra took to a pokéball to stay constantly at her side.
Mesmer later went through the maze game a vengeful classmate Otogi Riye created to put Yuumi through, and was the one that teleported her and Katsumi out of Otogi's burning gameshop, after Yuumi reassembled her Puzzle. He also came back to the island and helped Yuumi capture a couple more pokémon to round out her team before Setsuna's tournament in the city, which added Jinx the Gothica and Magna the Magnemite to her allowed party of six. Now he's in that tournament, and while a couple pokémon have been swapped along the way as Yuumi wins new ones from opponents, Mesmer remains a regular in her team, and likely will to the end, being the first and most trusted of Yuumi and Yami no Yuumi's pokémon.
Goomba the Dugtrio ♂
Ground
Catcher: Mutou Yuumi
Item: Bright Powder
Jolly nature.
Somewhat like a clown.
Arena Trap
Magnitude // Sucker Punch
Mud Bomb // Dig
On Pegasus's Island, the competitors had to battle each other for the right to catch any pokémon they came across at once, and that was the case with Goomba. Mutou Yuumi & Inspector Haga came across the then Diglett at the same time, and Yami no Yuumi led Mesmer to defeat Haga's Venomoth. After that the Diglett gave Yuumi, her friends, & the tired Mesmer a merry chase before they finally cornered and caught him.
Despite all the trouble Goomba proved a happy member of Yuumi's team, coming to her already strong and willing to fight. This is likely why he evolved so quickly during Yami no Yuumi's duel against Setsuna, creating two triplets of himself. And the new Dugtrio would have won that battle, if Yuumi hadn't held the spirit in her back when Setsuna put her life on the line. As a result Goomba was near killed, and the trust rift between the pokémon and Yuumi was near as bad as the one between the two souls inhabiting the trainer. That rift only really healed while she was facing Pegasus, when she refused to give up faith in her pokémons' ability to win the unbelievable fight. Since then Goomba's kept his own faith in his trainer, and gone on to defend her in a few fights in Battle City, including going head to head with the legendary bird Osiris.
Outside of battle, Goomba isn't allowed around the Mutou house much since he drills holes in the floor, but Yuumi will take what chances she can to give him time to play and dig, such as on Pegasus's Island. She's also gotten in trouble a couple times at the city park, when Goomba got loose there - he's not allowed out there, either, but he tends to try and sneak out of his pokéball to explore. He prefers Yuumi a little over the spirit she hosts, but that really just translates to he causes the vessel the most trouble.
Magna the Magneton
Electric/Steel
Catcher: Mutou Yuumi
Item: Shuca Berry
Relaxed nature.
Capable of taking hits.
Magnet Pull
SonicBoom // Spark
Electro Ball // Lock-On
Yuumi caught Magna as a Magnemite on Pegasus's Island after the Battle City tournament was announced, and she came to fill her roster with more pokémon and train the ones she had. As the first of the two she gathered, Magna was given a fair amount of time to train itself in the search, and the first fights of Battle City powered it up so much it evolved when Yuumi used it in a tag battle with Setsuna against the Masks of Light & Darkness, winning the fight and earning its trainer some much wanted credence in the CEO's eyes.
Magna is a calm pokémon that tends to keep to itself, listen well in battle, and only presses to come out when it's hungry. While Yuumi struggles sometimes to find a power source to feed it that's readily available and doesn't shoot up the electric bill so high her mom notices, Magna thankfully seems to get by well on sunlight, so she brings it along on her park visits.
Jinx the Gothita ♀
Psychic
Catcher: Mutou Yuumi
Item: Sitrus Berry
Naive nature.
Mischievous.
Frisk
Fake Tears // Psybeam
Faint Attack // Psyshock
Yuumi caught Jinx towards the very end of her second stint on Pegasus's Island, preparing for Battle City. As such she hasn't had much chance to train or interact with her yet. But what little they've done is worth mention, as Jinx helped Yami no Yuumi defeat Pandora's own Kadabra and was one of the pokémon she fought against Osiris with. She's rather fond of Yuumi, but the one Jinx tends to listen to more is the spirit of the Pharoah, as she instantly attached to her upon capture. Jinx is also one of the pokémon that tends to wander from her pokéball, though less from a wanderlust like Goomba than an oblivious curiosity of her trainer's environment.
Red Eyes the Honchkrow ♂
Dark/Flying
Catcher: Jounouchi Katsumi
Item: Figy Berry
Adamant nature.
Quick tempered.
Super Luck
Astonish // Pursuit
Wing Attack // Swagger
Katsumi caught Red Eyes on Pegasus's Island, after she won the right to try against Dinosaur Ryuzaki. She trained the then Murkrow well and he quickly became her favorite pokémon, so much so Katsumi followed Yuumi back to the island less to capture more pokémon for the upcoming tournament, than to find a Dusk Stone to help Red Eyes evolve.
But this ended up making the new Honchkrow attractive to the Ghouls around the city, and when Katsumi lost to a member that jumped her in an alley the Ghoul stole him. This fueled her to hunt down the thief when Battle City started. Some tension erupted between her and Yami no Yuumi, because the spirit insisting on fighting the Ghoul for answers about Marik, rather than let Katsumi fight for her Red Eyes. But the two let it go after Yami no Yuumi won, and Katsumi refused to take back her pokémon. Instead she told Yami no Yuumi to take care of him, so Red Eyes could stand as a promise between them to fight each other, as she would only take him back if she won him off of Yami no Yuumi herself.
That promise fueled their fights from then on, and when Yami no Yuumi battled against a Katsumi posessed by Marik, she used Red Eyes to remind her of that promise, and it helped Katsumi fight for control - afterwhich control was switched to Yuumi, who passed the Puzzle over to her friend as a sign of faith. The battle was for all purposes a draw, since the timer on it ran out, but they would go on to call it a mutual win. As such for the time being Red Eyes remains part of Yuumi's team.
Outside of battle, the tough bird doesn't get on too well with Yuumi's own pokémon. While the pharaoh's spirit tries to care for him herself - seeing his maintenance as her responsibility until he's returned to Katsumi - he tends to snap at her and look to Yuumi for his food and care.
Osiris the ZapdosElectric/Flying
Catcher: Marik Ishtar
Item: N/A
Rash nature.
Strong willed.
Pressure
Discharge // Pluck
Charge // AncientPower
Where exactly Osiris comes from is a mystery. The information listed in KaibaCorp system gives Marik Ishtar as the original catcher, but leaves out where he found it. Whatever the case Yami no Yuumi won Osiris by defeating it in the hands of Marik's puppet Strings, using Goomba and Jinx. She hasn't summoned it since and there's been no chance to interact with this pokémon yet, since its new trainer went from battle to battle right up until she dropped into the Dressing Room. But if it is brought out it'll likely be Yami no Yuumi who does it, as Yuumi is hesitant to try controlling it, while even the pharaoh's spirit has trouble bending its will to behave. As such she would hesitate to use Zapdos even as a last resort.
Pokémon Stored by KaibaCorp
Inaccessible in the Dressing Room
Crag the Aerodactyl ♂
Rock/Flying
Catcher: Mutou Yuumi
Lonely nature.
Alert to sounds.
Rock Head
Wing Attack // Supersonic
Agility // Crunch
Blast the Tirtouga ♂
Water/Rock
Catcher: Mutou Yuumi
Item: N/A
Rash nature.
Likes to thrash about.
Sturdy
Body Slam // Rollout
Aqua Jet // Brine
Arcane the Kadabra ♂
Psychic
Catcher: Pandora
Item: Psychic Gem
Sassy nature.
Strongly Defiant.
Synchronize
Psyshock // Reflect
Recover // Psycho Cut
Scourge the Yamask ♀
Ghost
Catcher: Mask of Darkness
Item: N/A
Naughty nature.
Proud of its power.
Mummy
Hex // Will-O-Wisp
Ominous Wind // Curse