Psychic-types often have special powers that make your opponent Asleep, Confused, or Poisoned.
Then, use a few Pokémon of a different type to cover your weaknesses (for example, using Fighting-types to cover a Psychic deck’s weakness against the Darkness-type). Each card type has a different play style, so choose one that matches the way you want to play as the primary focus of your deck. There are 11 types of Pokémon in the trading card game, but including them all in your deck makes it difficult to draw specific cards you may need for your strategy.