I have to say, I almost completely disagree with all of this.
Fairies being "seely or unseely" has very little to do with dogs, superstition of dogs, or "unclean events" having to do with dogs. You don't mention an example of unclean dog tropes here. You could've brought up the Barghest, a supernatural dog that eats corpses and resembles a cross between a ghoul and a hellhound. That would be more like Houndour or Houndoom, and is certainly not relevant to Snubbull, which in its Pokedex is very clearly a dog.
Straight-up, normal dog. People like to play with it because it's affectionate.
Furthermore, you say "when looking at it through a mythological aspect it is made clear that even snubull can be called the fairy pokemon." In what way are you suggesting this is clear? You've done nothing but make an unsubstantiated stretch with zero backup for it at all.
Also, it is *nothing* like angels. You seem to be making a comparison between fallen angels and "unseely" fairies.
Snubull was originally a Normal type pokemon, and was included into the Fairy type after its creation solely because of its pink color. That's it and nothing more.
No angels, no unclean dogs, no mythological aspect. It's pink. It's a recurring theme through the Fairy pokemon, which are less like Fairies and more like "things little girls would like." Case in point - Sylveon has no Fairy traits aside from being pink and having ribbons, which have less to do with the Fae and more to do with the interests of little girls who might be playing Pokemon.
TLDR: Your above claims are utterly groundless, please don't say them like they're facts if you're not going to back them up at all. Snubull is a Fairy type now because it is pink, and that's the extent of it.