Be careful! It's toxic! This dragon has some strange eating habits. He loves to have some sulfur for breakfast and radioactive remains for lunch, although he is on a diet now so he only gets a couple of old batteries for dinner.
All of the dragons listed below can be used to counter the Toxic dragon in fights, since all of them deal Critical (super effective) 2X damage against the Toxic dragon, but the Toxic dragon does not deal critical damage to any of these.