Psychic-types have been a fairly popular type since Generation I. Offensively speaking, they often have great Special Attack meaning they can deal damage quickly using STAB moves. Furthermore, Psychic-type Pokémon can often learn moves of other elemental types, to deal with a multitude of types, most especially their weaknesses of Dark, Ghost, and Bug. As a special sweeper, they are one of the best types in the game as a Psychic Pokémon's speed is also typically quite high.
Their defensive capabilities are often weak, however, in spite of some Psychic-types featuring moves such as Recover (Alakazam, Mewtwo, Deoxys, Latios, Latias, Starmie, Celebi, Chimecho, Medicham, Lugia). Psychic-types often have excellent Special Defense, but very low Defense and HP. Because of this, they can often only survive Special-based hits, and can easily be defeated by one or two high-powered moves from a Pokémon with an average or above-average Attack stat. Psychic Pokémon also often fall to a single Crunch. There are exceptions to this, such as Bronzong or Metagross, who have high defense due to their second type, Steel, and their lack of weakness to Dark-type moves.
When used in contests, Psychic-type moves typically become Smart moves, but can also be of the other four Contest types, excluding Tough.
In total, there are 53 Pokémon with the Psychic-type.
Psychic-type Pokémon are at the center of a balance issue in the Generation I games. The issue arose from the lack of an effective countermeasure against Psychic-types caused by the absence of any powerful Template:Type2 moves (at the time the only elemental weaknesses of Psychic-types). Additionally, Psychic-types were not affected by Template:Type2 moves in Generation I, causing further imbalance, although there were no powerful damaging moves that were of the Ghost-type anyway, except for Night Shade, which does fixed damage. Additionally, the only Ghost-type Pokémon (the Gastly evolution line) were all part Poison, which is weak to Psychic moves.
The issue was rectified in later generations with the addition of more powerful Ghost and Bug-type moves, pure Ghost-type Pokémon, the addition of the Template:Type2 (which are resistant to Psychic moves) and the Template:Type2 (which are both immune to Psychic moves and powerful against Psychic Pokémon themselves).
