Through the smog- evo

Koffing are actually genetically altered pokemon.

Originally they were a type of floating mould, but a group of scientists wanted to see if they could speed up its evolution as it had amazing abilities to break down toxic waste. They succeded, however the didnt realise that it produced poisonus gas's aswell as distrying it. They imprinted a toxic warning into its dna that showed up on its skin, to warn anyone who got too close. The programme was thought terminated but unknown to them two had escaped and started to breed.
Potentially this accident has become a good thing as the worlds toxic waste has been cut in half since then, but peope are still getting too close to these creatures and many people have been found to be extreamly allergic to them.

Koffing can float like ballons as they produce hydrogen and methane within their body. When they want to go lower they release it from scared crators on their surface, letting out powerful gas's.

They absorb toxic waste and rotting matter as they ahve no internal organs to speak of.
The matter gets broken down into gas or energy for its poisonous body.

Some have been known to live near volcanos and feed off the toxic gas and ash that is up there.
But they are very volitile, and you must be very careful with them with fire because if the fire ignites the gas, they can make large explosions.

mentally they are aware of their surrounding and can take orders but they have a very low IQ and can easily get confused. that is why if any trainer chooses to capture one of these then they must take extreame caution.

Hope you like it