Description
1) Its name in Japanese comes from Gangrene, which means "Death and putrefaction of the body tissue" and from Edgar Allan Poe, famous horror writer. Japanese: Gangar (Gangrene + Edgar)
2) If you have looked in detail at the design of this Pokémon, you will notice that on its back it has three rows of spikes on its back, however, in the first generation of the games Gengar is presented without its characteristic spikes.
3) As you know, there are a wide variety of users of the Levitation ability. Did you know that Gengar is the only one of them who, despite having such an ability, is always standing on the ground in his sprite?
4) Gengar has a weight of 40.5 Kg in the Pokedex, which is quite a lot if we take into account its high speed, and that its pre-evolutions simply weigh the paltry amount of 0.1 kg (adequate weight if we take into account that we're talking about ghosts)
5) For a time there was a theory that Gengar was Clefairy's evil twin, due to their similarities in both the design of his body outline, down to the spikes on his head and back.