leading suggestions: (will edit when more are suggested)
-Spike as an Equestrian equivalent of Zorro (would need a pony name/pun)
-Rarity as either her Shadow Spades cosplay or a pony version of Carmen San Diego (Carmine (red shade) San [insert horse pun]? Carmine Sandy [horse pun]?
-CMC with a group costume, possibly Equestrian equivalent PPG or 3 fairy tale characters
(more to come)

Read More