As you can probably tell, there's a different pony underneath the costume. The card's info says:
Ponyfication
Normal Spell
Select 1 monster your opponent controls and 1 "My Little Pony" monster in your Graveyard. The selected opponent's monster becomes the selected "My Little Pony" monster in your Graveyard and gains that monster's effects but it cannot attack or be Tributed.
Rainbow Rare