You must build a deck that consists of 60 cards. There are some decks that have 30 and some that have 40, but the most poplar deck is the 60 card deck. You should have about 30 energy cards (about the same amount of Pokemon in your deck). The best trainers are Pokémon Catcher and Pokeball because you get Pokémon and prize cards. You many only have up to four of the same Pokemon or trainer in your deck.