The first step to building a strong deck is to decide what Pokémon to use. Developing a strategy around the Pokémon's abilities is paramount. Once a strategy has been chosen, cards may be selected to support that strategy.
If opting for a deck with evolved Pokémon, deck-builders must also include previous evolutions of the characters. In general, it's advisable to include roughly the same number of evolved Pokémon as the one it from which it evolves. For instance, a deck with three Raichu should also include three Pikachu. Limiting the number of different Pokémon included in a deck is a useful strategy so that there is enough room for Trainer and Energy cards.
Once the Pokémon are determined, the next step is to decide on the number of Trainer and Energy cards to include. A traditional deck with Evolutions has 16 to 20 Pokémon and 30 Trainers plus 12 Energy. If using fewer Pokémon, there is room to expand the number of Trainers and Energy.
Trainers are the core of any deck. They enable players to find cards at the right moments and also execute strategies whenever desired. Likewise, having enough Supporter cards is key to a competitive deck. Many effective decks have approximately 14 Supporter cards.
There is a tremendous amount of flexibility in choosing a Pokémon deck. While these are suggestions, players may prefer to create their own versions that wind up being even more effective than if they had followed these guidelines.