Koffing is a round, limbless purple Pokémon filled to the brim with toxic gases. Several crater-like protrusions on this Pokémon's thin body give it the resemblance of a meteorite or a naval mine. Although Koffing is usually seen with only two small fangs in its mouth, it has a full set of flat teeth. Koffing has a skull and crossbones below its blissful face. Koffing has been considered to be related to Grimer, who is also a purple Poison-type Pokémon that associates with pollutants. Koffing may also be related to Drifloon, who is also a floating, round, purple, "X"-bearing Pokémon with a tendency to explode.
Koffing spews out poisonous gases whenever it gets upset. On the other hand, Koffing exhales fresh, clean gases whenever it becomes happy or overjoyed. Although Koffing's gas is more commonly attributed as being poisonous, the gases may also cause coughs, sniffles, and teary eyes. Koffing has also been known to explode from over-inflating its body. Koffing is also capable of launching Fire and Electrical attacks. As shown in the anime, Koffing's gas can be ignited by fire or electricity, which suggests that it also contains flammable hydrocarbons.
If Koffing becomes agitated, it raises the toxicity of its internal gases and then jets them out from all over its body. Koffing is prone to over-inflating its round body before it self-destructs. The higher the temperature, the more gas Koffing concocts.
Koffing floats in the air because its body is filled with a gas that is slightly lighter than air. The gas is a combination of the vapors from fermenting trash and Koffing’s own poisonous fumes.
Koffing are a very common sight around burned-down or abandoned buildings and power plants. Volcanoes also provide a suitable habitat for them. They are common in Kanto and [[Johto].
Koffing mainly eat rotten kitchen garbage.
This Pokémon was unavailable prior to Generation I.