So there's a lot of discussion about real life animals in Pokemon, but I recently had this thought while reading a youtube comment about someone thinking there'd be a real dragon in Dragon's Den. What do you think about the idea of there being non-Pokemon mythical creatures in the Pokemon world?

Technically we already have these with ghosts, but let's go beyond that. Things like dragons, shinto gods, kitsune, the Touhou shit, and more. Could these work? Could they have worked in the early-gen Pokemon world, but not now? How would you imagine them implemented in Pokemon?