>>28077614Poison is not a bad type since it resist 5 types, including fairy and fighting, immune to the poison status (Salandit aside), can absorb toxic spikes, and has a recovery item in the form of Black Sludge.
What Poison mons are lacking is the a decent move pool (only good offensive moves are Poison Jab, Gunk Shot, Sludge Bomb / Wave), great stats (see picture), and abilities (1/4 of them have Poison Point and other weird shit)
Poison being SE against Water is asking for too much. If anything, it should probably resist it.
