According to the latest edition of Japanese magazine CoroCoro Comic, Youkai Watch is heading to 3DS; the game was first announced by developer Level-5 one year ago at its Vision event.
Youkai Watch is all about a boy who wears a special watch that allows him to see and interact with ghosts, and similar to Pokémon-style battling he can then fight them using his own ghosts. Level-5 described the game as another multimedia franchise along the lines of Inazuma Eleven.
Please bear in mind this is currently only a rumour and that localisation could be far from guaranteed, but we'd love to hear if this is the kind of game you want to see on 3DS. You can check out the trailer below, which was released last year.