Could be a little bit of both. That would be interesting if they did make some of both. Maybe they can throw some DS and GBA type levels in the mix.
Hopefully they can all be unique in their own way. They had no problem with level uniqueness with the previous titles, but for this one they can have at least 30 levels when you think of the different game available that can inspire them.
Same goes with characters, now they had a uniqueness problem with them. Several characters had the same character models and mechanics (examples: Ganondorf and Capt. Falcon, Fox and Falco, Mario and Luigi and Dr. Mario). Maybe they change them, seeing it is a new system with new controls.
Speaking of, maybe they can have some new moves added to them as well. Say like Ganondorf can use that big energy attack he used in OoT, or for Link some of those cool moves he uses in Twilight Princess, or maybe the spider ball for Samus.
Makes me wonder what we can experience with this new SSB.........