Allow /pokebattle to accept '<'player'>' and '<'NPC Trainer'>' as the two parameters. Or just make /pokebattle3 a new command that allows a 1v1 battle between player and chosen NPC Trainer.
I agree, an updated /pokebattle would be fantastic. For a custom map I wanted to force a battle with a golden pokemon, but couldn't put '<'pokemon'>' or the pokemon specs as arguments.