>>13810728There was some guy who made a video where he talked about the legendaries being based off norse mythology, with yggdrasil having a blue-eyed bird at the top, four differently-coloured stags in the ground, and a corpse-eating snake at the bottom.
I'd say a rock or ghost/poison legend would be plausible. Especially seeing as I can't really see gamefreak doing anything else shaped like the letter Z, but that's just lack of imagination.