Poison types are great defensively. Maybe I was gimping myself, but I ran a pretty decent mono-poison team in gen 5, and toxic immunity/resistance to fighting was a godsend. Not to mention there's a lot of poison tanks like Weezing and Amoonguss.
Don't get me wrong, it was still the worst attacking type (and likely still is other than normal), but saying its the worst type is a bit of a stretch when they have a few merits. The fact that most poison moves carry a chance of regular poison sucks, since it typically makes their moves have less BP and regular poison is objectively the most useless status effect in the game.
