Not without hacking.
you dont
Action Replay
If you mean another trainers Pokemon you have to use cheat codes
to catch another trainers Pokemon on pearl you have to have an action replay system or some kind of flash card
You can't steal Pokemon however in Pokemon colosseum and Pokemon xd gale of darkness you can snag shadow Pokemon from trainers.
You cant catch another trainers Pokemon. However, if you find the same type of Pokemon in the wild you can catch it. Not even a master ball will catch another persons Pokemon.
This is the code for "Catch Trainers Pokemon" B6C5368A 08BE8FF4 B8D95CFE 06ED6EA1 E151C402 8A229A83 8E883EFF 92E9660D Press L+R in battle to be able to catch trainers pokemons as if they were wild.
only if you have the catch trainers Pokemon code
You cant catch any trainers Pokemon
no
you can't
No im sorry, it is not possible. But if you look up where to find the Pokemon, then go to that area and catch them yourself. Every trainer has a Pokemon that you can catch, you just cant catch theirs. what kinda Pokemon watching freak r u!!!