hammers, torches, and frogspawns can touch each other because they use the same toxins. If a hammer tries stinging a torch, and the torch is immune, then there is no point, and thus no poising. Zoos will not sting each other, ricordeas will not sting each other. What you have to be worried about is SPS stinging other SPS and soft/LPS. I have heard loads of stories where peoples Blastos or Acans wind up sting montis, especially encrusting ones.