- Voice actor: Eric Stuart (both English and Japanese)
Weezing mostly look like two Koffing stuck together, albeit both being a lighter shade of purple than an actual Koffing, with one being larger than the other is. The larger head sports the skull-and-crossbones design featured on its pre-evolution, while the smaller head only has a light yellow circle underneath the face. It also has a third chamber on its underside, presumably for storing extra toxins, which resembles a tiny version of a Weezing head, minus the face and skull-and-crossbones pattern. Two small appendages connect this extra chamber to the heads. The larger head has prominent eyebrows, pointed teeth protruding from its lower jaw, and flatter teeth on its upper jaw, while the smaller head simply has two pointed teeth, one at each corner of the mouth. Triplet Weezing have been discovered, although they are extremely rare. Weezing's height is 3'11" and weight is 20.9 lbs.
Each head contains a different toxin. When one head inflates, the other deflates, mixing the gases. By doing this multiple times, it becomes more toxic and noxious, although it does have the side effect of making Weezing smell worse. Weezing is capable of expelling this gas in order to attack its enemies, and can also attack with globs of sludge. Ironically, exquisite perfumes can be extracted from Weezing's toxic secretions. A Weezing is capable of generating electricity, as well as breathing fire. It is also capable of exploding. In rare cases, a Weezing can also exhibit signs of limited psychic power. Like it pre-evolution, Weezing's gas contains flammable hydrocarbons, which makes it volatile and easily ignited by fire or electricity.
A Weezing will find a dirty, unkempt house and nest there. At night, when the people in the house are asleep, Weezing will go through the trash. It constantly inflates and deflates its heads to mix its poison gases.
It has been explicitly stated that Koffing, Weezing's pre-evolution, is able to hover in midair due to its gases being lighter than air. Although the same has never been explicitly stated for Weezing, it can be assumed that this is the case, as Weezing displays an ability to float in midair seemingly identical to Koffing's ability. It is, however, a known fact that a Weezing's gases are less dense than water, enabling it to float on the surface of water effortlessly, although this also means that Weezing is essentially unable to spend any amount of time underwater.
Weezing live in urban and suburban areas, and can often be found in dirty, unkempt houses. Active volcanoes are also a good place to find them.
- Main article: Pokémon food
Weezing feed on the dust, microorganisms, and especially gases emitted by garbage and toxic waste. Weezing consider gases that emanate from garbage to be the ultimate feast.
Ash used a Weezing in a Pokémon League entrance exam in The Ultimate Test. It defeated the instructor's Flareon with its Smog, Smoke Screen, and Tackle attacks. Later on, Ash commanded it to use Explosion against Team Rocket, causing them to blast off.