>>24526634Medium exclusive mons
In anime that would be: Pink Butterfree and other pink ones shown in OI episode, Film 4 Unowns (one looked like Russian Я letter), Dark Celebi and Dark Tyranitar of Vicious, Aeorodactyl/Kabutops Fossil MissingNo. Annie and Oakley used, Armoured Mewtwo, Fake Groudon, MechaMew2 (PokeLive), Venustoise, Mismagius-Rayquaza,
Manga: Zapmolcuno, Blockhead Clefairy, Marin
TCG: Dark Arbok (and overall various Arbok patterns)
Games:
Primal Dialga, Shadow Lugia, Dialkia (also manga), Spiky-Eared Pichu, ??? Arceus, other MissingNo. forms and those placeholder sprites used for ?????????? and ? in third gen (the latter was from beta of R/S when you didn't seen pokemon), Surfing Pikachu and Flying Pikachu (also manga)
I'm not really sure, did these sprites even differed between R/S and X/Y?
If you need more inspiration check:
http://www.deviantart.com/art/Glitches-Pokegods-Beta-Pokemon-Special-Pokemon-289236024 , I'm sure there was a lot more of that stuff.