a Pokemon - Absol. Because they're awesome.
Gym Leader - Psychic with an Alakazam and a female Meowstic.
A Trainer - I would raise cute Pokémon (Absol, Growlithe, Flareon, Meowstic, Whimsicott), lol.
If you had any Pokemon Ability - Super Luck. Because that would be useful at all times.
If you had any Pokemon, which one would you have - Meloetta. Because she can sing and cause happiness.