Trainer Card
Retaliate
If there is a trainer card on top of your opponent's discard pile that he/she played last turn, you may use the effect of the trainer card once during your turn. If your opponent's card is a supporter, you may not play any supporters from your hand during your turn. You may not use Retaliate if your opponent's card is also Retaliate. Discard Retaliate at the end of your turn.
I think this would be a fun card. Use your opponent's own cards against him/her. This would make people think twice about playing some trainers for fear of helping their opponents.
Retaliate
If there is a trainer card on top of your opponent's discard pile that he/she played last turn, you may use the effect of the trainer card once during your turn. If your opponent's card is a supporter, you may not play any supporters from your hand during your turn. You may not use Retaliate if your opponent's card is also Retaliate. Discard Retaliate at the end of your turn.
I think this would be a fun card. Use your opponent's own cards against him/her. This would make people think twice about playing some trainers for fear of helping their opponents.