According to director Masahiro Sakurai, whatever form of interplay the Wii U and 3DS versions of Super Smash Bros. will feature won’t be cross-platform play.
“Since each version of the game has completely different stages, cross-platform play wouldn’t work,” Sakurai told Joystiq.
According to Sakura, some form of character customization is what will carry over from one version to the other—but again, what the customization is, exactly, remains a mystery. The only thing Sakurai was willing to confirm was that the customization would not be visual. As far as the game’s director is concerning, altering the appearance of characters would take away from their individuality.
Best guess? Customization Super Smash Bros. will either deal with move sets or how the characters are balanced.
Super Smash Bros. for Wii U and 3DS was revealed during the special E3 2013 edition of Nintendo Direct. The game is set to launch on both platforms sometime 2014.