A couple of years ago, we heard that the 3DS and Wii U versions of Smash Bros. would interact in some way. Masahiro Sakurai has confirmed, however, that this is not in the form of cross-platform play. A player on the 3DS will not be able to verse a player on the Wii U, basically. But we do know now that “players will be able to take characters they’ve customised and transfer them to the Wii U version”.
What are these “customisations” though?
We have no idea. Sakurai only said that “they won’t be costumes and they won’t be something that players have to unlock through repetitive tasks”. In the mean time, feel free to guess.