Pick what prize you get!
You know when you knock out a Pokemon, you get to pick a prize? Well after you knock out one of you apponent's Pokemon, you pick your prize and if you don't like it, you turn off your game boy. ( Don't worries, this will not erase your data.)
Turn your game boy back on and it will return to your last turn before you knocked out your apponent's pokemon. Knock the apponent's Pokemon out again, and you can pick out a different prize! Do this untill you have found the one you like.
If there is absolutely one you don't want, well you'll just have to pick ONE of them.