Quoted By:
I think this is because back in the 90s during Pokemon's original heydey, a LOT of other tv shows and comics woukd do their own homages/parodies. More than one parody/joke/reference Pikachu piece of artwork had a black tip on its tail or some other kind of inaccuracy....most likely to avoid copyright infringement.
Also, there were a LOT of bootleg cards and tots around back i n the Red/Blue/Yellow days as well, and we have all seen wonky and weird looking bootleg Pokemon figures. Lots of Not-Pikachus out there had black tails, green cheeks, etc etc.
