Steel. These Pokemon include: Empoleon, Steelix, Mawile, etc.
Poison types are weak against Ground and Psychic types.
The weaknesses of poison types are psychic and ground.
Poison-types and steel-types
ground type Pokemon are super effective against poison type Pokemon.
Jessie has had poison and bug types, while James has had poison, grass and psychic types.
Poison types are the only Pokemon that can't be poisoned. All there is to it
Psychic types are super effective against Poison types.
Poison types are weak against Ground and Psychic types.
Steel and other poison types are not effected by poison.
The weaknesses of poison types are psychic and ground.
Ground types and psychic types beat poison types.
Poison-types and steel-types
ground type Pokemon are super effective against poison type Pokemon.
Jessie has had poison and bug types, while James has had poison, grass and psychic types.
Poison Type moves are super effective against only Grass Types.
Actually there is no Pokemon fully unaffected to fire types but there are some that are resistant like water, ground, and rock just examples
Psychic. (: