Psychic and ground type moves are super-effective against poison types I tried using fighting moves, and they were not very effective
Poison and Steel types are super effective against Fairy types.
Gengar is a ghost/poison type so... ghost and dark types are super effective against ghost types. ground and psychic types are super effective against poison types
Poison Type moves are super effective against only Grass Types.
Bug types are super effective against Dark, Grass and Psychic (x2) in Generation II-onward. In Generation I, they were super effective against Grass, Poison and Psychic.
Poison and Steel types are super effective against Fairy types.
Poison and Steel types
Psychic and ground type moves are super-effective against poison types I tried using fighting moves, and they were not very effective
Poison and Steel types are super effective against Fairy types.
Psychic types are super effective against Poison types.
Gengar is a ghost/poison type so... ghost and dark types are super effective against ghost types. ground and psychic types are super effective against poison types
In Generation 1 (Red, Blue, Yellow) Bug is super-effective against Poison, and Poison is super-effective against Bug. Weedle Kakuna Beedrill Venonat Venomoth
Poison Type moves are super effective against only Grass Types.
Bug types are super effective against Dark, Grass and Psychic (x2) in Generation II-onward. In Generation I, they were super effective against Grass, Poison and Psychic.
Poison and Steel types are super effective against Fairy!
Fighting and Poison. It is not very effective on Steel, and has no effect on Dark.
Fairy types are weak against Poison and Steel types, and their attacks aren't very effective against them or Fire types.