The following info comes from a Joystiq interview with Masahiro Sakurai.

- each version of the game has completely different stages
- cross-platform play wouldn't work
- each version will interact with one another
- take characters you've customized and transfer them to the Wii U version
- customizatios won't be costumes and they won't be something that players have to unlock
- different costumes would take away from what makes each character unique
- wants to avoid boring, repetitive tasks
- "stress free, easy connectivity" between the two versions
- no comment on level editor