Poison is an element found in the Pikmin game series, and found in many, many Fanon games. Poison hazards refer mainly to small pipes sticking out of the ground which constantly emit poisonous gas which suffocates Pikmin; whistling at a choking Pikmin will save it instantly. White Pikmin are totally immune to poison gas and are the only ones capable of destroying gas pipes. Because the air is thoroughly filtered, captains wearing a spacesuit will not succumb to poisonous gasses.
Some enemies also utilize poison as a weapon, for instance, the Doodlebug leaves behind clouds of toxic gas. Some enemies also use poison as a defensive covering, like the Toxic Bulblax. White Pikmin generally should be used against poison-wielding enemies.