>>43590203???
Gengar has been a shillmon since inception
It is the first pokemon you see when you turn on R/B
It has always been prominently featured in any promos or merchandise for the game since R/B
It has great stats, typing, and movepool, and has been relevant in every metagame other than gen 7 (where it was still completely usable)
It's an appealing, simple design that makes for a good mascot character.
