"Gas" is technically a state of matter, nothing more. Granted, it is frequently used to refer to either "natural gas," which is a naturally occurring mixture of gases, as well as petrol/petroleum fuels. However, both uses are, technically, incorrect, though "natural gas" is at least closer to the proper use, due to its makeup.
Founder - IRDC AND Fluffy the Friendly Deathclaw Fanclub ULCE#: 9,426 of 53,160; Misty is mine!
BTW, you need Oxigen to have fire. Those Pokemon cities need much more trees for them to be a safe place to live
Gases with carbon in them extinguish fire. Keep in mind in order for fire to be sustained, it requires fuel, not just oxygen and a spark, and the distribution must be just so. Thus, Gastly would not catch fire unless it consisted of a hydro-carbon compound such as gasoline, alcohol, sugar, etc, which is highly unlikely, and even then, because gastly is dense enough to stay in one piece, there is no air within Gastly's form. Stoichiometry is key to ignition.
Bazinga! *dives into ballpit* Pokemon Black Friend Code: 0605-2800-9952; Trainer Name: Solace; First Pokemon (roleplaying): Shiny Umbreon