Premier Ball is an excellent Trainer, though its usefulness is somewhat limiting. Basically, you get to search either your deck or DISCARD for a Lv X and add it to your hand. This is a great, cheap way to search out your needed Lv X; however, it's overall usefulness is limited in that most decks only run 1-3 Lv Xs. Still, it's a lways worth considering if you use them.
Modified - 8/10 (A great search card, but limited in that it only finds Lv X)
Limited - 10/10 (If you play a Lv X here, you will wan tt his card to get it. Otherwise, you have no need for this card)
Unlimited - 1/10 (Who uses Lv Xs in Unlimited?)