This idea came around after reading a few fics where Pokémon crossed over into MHA. But all I usually see is either Izuku as a trainer in a Pokémon world, or Izuku with Pokémon abilities. So, I thought, why not make one where he can use Pokémon similar to a Trainer, but make it so he is one of the only ones to use Pokémon, as it would be a quirk.

Quirk: Pokémon Master
Definition: the quirk enhances all physical and physiological features of user; user gains two items: a belt that contains PokéBalls (will be able to switch the Pokémon on his belt with the next item) and a fingerless gauntlet that acts as a RotomPhone. When the quirk has evolved, the gauntlet will obtain a Key Stone, Z Ring, and a Dynamax Band.
Drawback: Requires Stamina to keep Pokémon outside their PokéBalls. Will result in fainting if overused.
Quirk will allow up to 3 Pokémon to be out when first obtained. Will also require a bond with Legendaries to be able to summon. Unable to summon Arceus, as he is god. Will also be able to bring out different forms of Pokémon. Can also gift PokéBall to someone, however, this cannot be gifted to others without user's express and visual consent. Also can summon all different Evolution Stages

This is also fairly balanced, and was actually the second quirk I ever wrote down, so I am kinda proud of it. And also, if you still think it's unbalanced, people use quirks where Izuku is 100x stronger than All Might. If that isn't unbalanced, I don't know what is.

Anyway, hope you like it, and if you have any questions, just give a shout, and I'll answer as quick as I can. Laters and enjoy!