Mega Hoopa is referenced in the first Pokemon games!
Remember when the NPC from Red/Green/Blue asks “Do you believe in ghosts?” She then proceeds to claim that there’s a white hand on the player’s shoulder. Now we finally have a Pokemon to link that hand with!
Hoopa is a to-be-announced Psychic\Ghost type legendary Pokemon capable of creating wormholes through the use of various golden rings. Take a look at its sprite. Therefore, as referenced in its sprite, Mega Hoopa is capable of using a golden ring to place its “white hand” on the shoulder of someone even in the Kanto region. Neat, eh?
Neat, but that’s not a reference to anything but a regular ghost. At that time the only pokemon existent besides the first 151 were the Gen II ones whose games were still in development.
Hoopa is a brand new pokemon.