Koffing was one of the more original Pokémon introduced in the franchise’s original Pokémon Red and Blue, eschewing the animal forms of most Pocket Monsters for a design that looks like both a ball of fuming gas, as well as a virus. The latter is also implied from its name, as the nasty miasma it releases tends to cause those around it to hack in discomfort.
According to the franchise’s anime, it also has a sickeningly intimate place of birth that could explain its toxic nature. Here’s the history of Pokémon’s most disgusting spherule of smoke, and the different places where it may have been discovered.
In the long-running Pokémon anime, the characters participated in a quiz about various Pokémon. One of the questions was about Koffing, revealing that the floating blob of bile was first discovered in a public bathhouse. This suggests that the species is a fairly recent discovery, as public bathing only became common in the 1800s in the real world. The Pokémon trading card game, however, suggests a different origin story for the Kanto original. In the Team Rocket expansion pack cards, Koffing is said to have first appeared in a weapons factory. This could be explained as either Jesse (who answered the quiz question in the anime) being incorrect, a retcon, or the world of the anime and the trading card game being separate continuities.
To most, bathhouses are a pretty disgusting concept, with large numbers of people bathing together in the same water. Thus, it would seem that Koffing somehow evolved from the collective filth filling the public forums. Though they have fallen out of favor for the most part in the West, bathhouses are still common in Japan, explaining the reference in the Pokémon anime. A weapons factory, while still likely unsanitary and filled with unclean air, would probably still be a lot more sterile in comparison. However, this munitions-based origin would explain why it physically resembles a naval mine.
Koffing appeared in the first generation of Pokémon games, where it could be caught in the spooky Pokémon Mansion. Upon leveling up to level 35, it can evolve into Weezing, which resembles a sort of conjoined twin version of its pre-evolution. It and Weezing were and still are some of the few pure Poison-type Pokémon, though this was recently changed with the release of Pokémon Sword and Shield. Set in the Galar region, Koffing remained unchanged, but the Galar variant of its evolution Weezing is now Poison/Fairy-type. This regional variant also sports a darker color scheme and filters air rather than polluting it. In fitting with its poisonous theme, Koffing’s preliminary name at the conceptual level was NY, in reference to the smog and pollution of New York. Weezing, on the other hand, was going to be called LA, homaging one of California’s more contaminated cities.
In the anime, Koffing had a fairly consistent role from the beginning, as a Koffing was a part of Team Rocket member James’ party starting with the series’ second episode. The species has continued to see major and minor appearances throughout the show and movies. Similarly, it has been a mainstay for many of the video games and can be caught in the wild in at least one main entry for each generation except VII. It has also been available in most of the spinoffs, which typically involve most of the more iconic Gen 1 monsters. Koffing has proved to be among the most enduring early Pokémon, floating out of the bathhouse and into players’ hearts.
One of the more iconic Gen 1 Pokemon, the noxious Koffing was found in a fittingly germ-laden environment.