Matadogas

Matadogas is a purple Pokémon consisting of two spherical heads connected by a thin tube with another sphere in the center. The heads have differing sizes and features. The left head is larger and has prominent eyebrows, pointed teeth protruding from its lower jaw, and two flat teeth in its upper jaw. The smaller, right head simply has two pointed teeth, one at each corner of its mouth. The larger head has a cream-colored skull-and-crossbones marking below its face, while the smaller head has a ring marking instead. It is covered with many geyser-like protrusions, which usually expel mustard-colored gases. Matadogas is said to form when poisonous gases pool and two Koffing fuse over many years. Very rarely, two Koffing can become a Matadogas in a short timespan because of a sudden mutation. Triplet Matadogas have been discovered, although they are extremely rare.

Each of Matadogas' heads contains a different toxin. It mixes its gases by inflating one head and deflating the other. When its gases mix, Matadogas becomes more toxic and putrid. Matadogas can hover in midair, presumably due to gases lighter than air, as is the case for Koffing. Despite their stench and poison, Matadogas' gases can be used to make top-grade perfume by diluting them to the highest level.

Matadogas lives in urban areas. It seeks a dirty, unkempt house and nests there. At night, when the people in the house are asleep, it will go through the trash. Matadogas feeds on the dust, microorganisms, and especially gases emitted by garbage and toxic waste. Matadogas' body expands and smells worse upon inhaling poisonous gases. The Kantonian Matadogas used to be common in Galar and created more potent toxins than their Galarian relatives.

(Source: Bulbapedia)