What is a weakness of ghost type Pokemon?

Answer 1

Ghosts have 2 weaknesses - Dark and Ghost.

Ghost attacks are weak against Dark types, but strong against Psychic types. They are also weak against other Ghost Type attacks.

The only ghosts who are weak to Psychic types are those who have a poison type as well, Gastly, Haunter, and Gengar.

Psychic > Fighting > Dark > Ghost> Psychic

Psychic attacks do regular damage to ghosts and are useless against darks.

Ghost attacks are weak against darks but strong against psychics

Dark attacks are strong against both psychics and ghosts

So when you take Alakazam vs Gengar, and use a Psychic move, it does reg damage to the Ghost type, but becomes Super Effective because of Gengar's dual-typed poison.

Take the same Alakazam against a Mismagius, and you'll get regular damage with Psychic moves. This is because Misdreavous is a purebred Ghost-type.

Take Alakazam against a Sableye, and you get nothing. Sableye is a dual ghost/dark and is immune to psychic attacks.

However, in the original Pokemon Red, Blue, Green, and Yellow, only Psychic types could hold well against Ghosts. This is because the only 3 ghosts of the series, Gastly, Haunter, and Gengar, are dual poison types. Therefore, Psychic types would work wonders., However, there is a special rule for Shedinja (A Bug/Ghost type), Due to it's ability, Wonder Guard, Which causes only moves that are super effective (Fire, Flying, Rock, Ghost and Dark) To affect it at all.