Darkness sometimes represent evil and crime, but Dark Pokémon are quite misunderstood there. Dark-type Pokémon are known for often using sinister and deceptive moves such as biting and stealing. Some Dark Pokémon include Sneasel, Absol, Poochyena, Umbreon and Houndour. This is also the only Pokémon type which does not have a gym (only some Elite Four members use them). They are often used by criminals as well. Dark Pokémon are usually seen at night, but they are seen in the daytime as well.
They are known as Darkness-types in the TCG.
They are weak against Bug and Fighting moves, but strong against Psychic and Ghost. They are also completely immune to Psychic moves.
If a two-typed Pokémon is both Dark and Ghost type, both types cancel out each others weaknesses with their resistances, leaving Pokémon like Spiritomb and Sableye with no weakness.
As of Generation 5, this is the only Pokémon type not to be used in a Gym.
As of Generation 5 there are only nine Dark type Pokemon (not including Dark-type Arceus) are fully Dark type, these are: Absol, Poochyena, Mightyena, Umbreon, Darkrai, Purrloin, Liepard, Zorua and Zoroark. Of these nine Darkrai is the only Mythical or Legendary (and the only Mythical or Legendary Dark type Pokemon excluding Dark-type Arceus), Absol and Darkrai are the only ones that either do not evolve or are an evolution, out of the ones that are evolved only Umbreon does not have the Dark type through the whole evolutionary line and out of the pure Dark types any evolutionary lines have only two Pokemon in each one and Dark type is the only type all the way through the evolutionary line.