Ghost types are also unique in the fact that they have a type-specific attack: Curse, which works differently for Ghost-type Pokémon than it does for other Pokémon. The move Trick-or-Treat adds the Ghost type to the target's types.
Since Steel-type Pokémon no longer resist Ghost-type attacks in Generation VI, Ghost is tied with Dragon for the least resisted type. No Pokémon resists a combination of Fighting and Ghost-type attacks, as the only combination capable of this (Normal/Ghost) has never materialized (except when Trick-or-Treat is considered).
In Contests, Ghost-type moves are typically Clever moves, but some may be any of the other Contest conditions.
As of Generation VII, there are 46 Ghost-type Pokémon or 5.7% of all Pokémon (counting those that are Ghost-type in at least one of their forms, including Alola Forms), making it the 2nd rarest of the eighteen types, only above Ice.
In Generation I, Ghost-type moves have no effect on Psychic-type Pokémon, though an abundance of evidence suggests that this may have been an error. Multiple sources mention that Ghost-type moves are super effective on Psychic-type Pokémon: official strategy guides published by Nintendo, two episodes of the anime (The Tower of Terror and Haunter versus Kadabra), and even the games themselves, where a Trainer in the Saffron Gym mentions that Psychic-type Pokémon "only fear Bugs and Ghosts" (though the reference to Ghost-type Pokémon was removed in Pokémon Yellow). This was corrected in Generation II to make Ghost moves actually be super effective against Psychic-type Pokémon.
There are no Ghost-type moves with an accuracy lower than 100%.
While the Ghost type has an immunity to Normal-type moves, several damaging moves that display as Normal can affect them, including Hidden Power (whose actual type varies) and Struggle (Generation II onward).
From Generation VI onward, it is not possible for any Pokémon to possess a double resistance to Ghost. The only Pokémon to possess a double resistance in previous generations are Pawniard and Bisharp, both of which are Dark/Steel.
The Ghost type is the only type immune to two types: Normal and Fighting.
It is also the only type to have ever been ineffective against two types: Normal and Psychic in Generation I.
Ghost and Normal are the only two types to be ineffective against each other.
In Pokémon Conquest, Ghost-type Pokémon which are not part-Flying or have Levitate are shown with an animation of physically passing through enemies, referencing the common belief that real life ghosts can pass through solid objects. They cannot, however, pass through any other obstacle on the field in-game.
Ghost and Dark are super effective against the same types. As of Generation VI, the only differences between them is that Dark-type moves are not very effective on Fighting or Fairy while Ghost-type moves do not affect Normal Pokémon.