EDIT: The grand finale of the "attire stealing" series can be found here (with Tiana!): [link]
Disney "princesses" aren't just into fluffy dresses...Maybe they're just trying to relate to their adversaries by walking a mile in their clothes?
Snow White: Wicked Witch
Mulan: Shan Yu
Cinderella: Evil Step Mother (weakest "villain" ever!)
Sleeping Beauty/Aurora: Maleficent
(c) Characters all belong to Disney