Which pokemon would be the best trainer?

They get six pokemon: grass, fire, water and then whatever types they want.

Which pokemon, out of all of them, becomes the world champion? Mewtwo? Mew? Alakazam? Celebi? Mr Mime? Porygon Z? Entei? Lugia (thought it was Luigi lol)? They have to make the strongest team (they don't fight, they're a trainer)

Mewtwo

Mewtwo is the best answer we have the most solid evidence for.

Nihilego through absorption became a trainer... so it at least understands how Pokeballs work and what to do with them.

Lucario? I don't think it would want to be a trainer

Zoroark could be a trainer though Illusion if it wanted to... so it probably could be a trainer.

Anyway if this isnt about what Pokemon would make great trainers.... then Arceus would be the best trainer... its God