>>44777184The anime doesn't show a lot of trading, probably for the reason I just stated. The anime has pokemon acting more human-like so removing their choice from the equation gets a little icky morally for the show. More often than not, we see Pokemon given away to an individual, Paul giving Chimchar away for example.
From what we know, Pokeballs are not mind altering devices, the Pokemon doesn't change disposition towards you or your friends just because you caught them. The games have stated if a Pokemon doesn't want to be with you, Pokeball or not, they will leave you.