I mean things like thsese:
|Bulbasaur = l | BulbasaurS = | BulbasaurF = t | BulbabasaurM = t
|Mewtwo = s | MewtwoS =
|Meltan = t | MeltanS = t
The function for grabbing the wiki URL for the image is returning the raw image URL on the fandom site. You should be able to use and abuse it if you wish. Those images are coming right off of this site.
Purified and Shadow Pokémon sprites do not appear any different from their standard Pokédex sprite entries. This would be a MASSIVE undertaking to make custom sprites by adding red eyes and throwing in a static shadow flame for EVERY possible sprite.