I'm honestly not that good a Poison user. I mean it's helpful, though my strategies tend to more at wiping out my opponents fast due to not usually having a tank. Thus, I tend to rely more on Sleep or Paralysis, as those are moves that ensure that'll I get a hit without the opponent necessarily hitting too. Confusion works too at times, with also giving the chance of the opponent doing damage to itself, however it's still not one I tend to use that much.