Battling against poison Pokemon can be hazardous because their signature status condition and toxic's increasing damage will get out of hand if you're not prepared for it!
GameFreak hasn't been kind to poison types because, in general, all of their stats are below average. But, that doesn't mean you can take poison type Pokemon lightly!
There are several poison type Pokemon that are notable exceptions to the rule and they all sport a number of useful defensive resistances.
Poison type Pokemon are weak to:
Use attacks of these types to deal double damage against poison types. It's super effective!
Steel type is immune to poison type attacks:
Use a steel type Pokemon to take no damage from an opponent's poison type attacks.
These types resist poison type attacks:
Use Pokemon of these types to take half damage from an opponent's poison type attacks. It's not very effective.
Great Pokemon to use against poison types:
These Pokemon learn super effective attacks or have useful resistances (or both!)
Claydol (ground / psychic)
Metagross (psychic / steel)
Steelix (ground / steel)
Bronzong (psychic / steel)
Nidoking and Nidoqueen (ground / poison)
Solgaleo (psychic / steel)
Read more: The ULTIMATE Pokemon Type Weakness Guide
Good attacks to use against poison type Pokemon:
Earth power (ground)
High horsepower (ground)
Zen headbutt (psychic)