In Hotel Mario, Wendy attacks by blowing kisses at you. There are two versions-There are red ones that look like a pair of lips (sorta) and home in on you, but disappear quickly. There are also pink ones that look like hearts with angel wings, and they last long, but they move randomly (usually not near you at all). I don't know if the pink ones have an additional effect or something, like maybe opening doors, but I don't think they would.
EDIT: I saw another video of this fight, they DO open doors. Here's the other vid btw, started at the Wendy fight. http://www.youtube.com/watch?feature=player_detailpage&v=mXPac-URdrM#t=211s