Koffing embodies toxic substances. It mixes the toxins with raw garbage to set off a chemical reaction that results in a terribly powerful poison gas. The higher the temperature, the more gas is concocted by this Pokémon.
If Koffing becomes agitated, it raises the toxicity of its internal gases and jets them out from all over its body. This Pokémon may also overinflate its round body, then explode.