"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."
Koffing is one of the Pokemon that you would associate with being "evil". Not because of its look per se, even though it is essentially a floating ball of poisonous gas, no, it's more like guilty by association. For it seems that virtually every evil group in the history of Pokemon using Koffing, including James from Team Rocket for many episodes.
Koffing's Basic Attacks are Acid and Tackle, while its Special Attacks are Sludge, Dark Pulse and Sludge Bomb.