Weezing

Weezing (Japanese: マタドガス Matadogasu) is a -type Pokémon introduced in Generation I.

Physiology
Weezing is a Poison Gas Pokémon. It is a two-headed, purple Pokémon. They often have gases around them because they are so toxic. The biggest head has a skull and crossbones on its chest. The mid-sized head only has a circle. Apparently, they can also have three heads according to the DPP Pokédex, possibly a deformed conjoined circle between the two.

Evolution
Weezing is the evolved form of Koffing as of level 35.

Trivia

 * The name "Weezing" is a homophone for "wheezing."