The 3DS version also has some sort of "marathon mode" tied to the 3DS pedometer, I'll have to go back and watch the footage to see what that was all about.
Why only Rosalina and Ludwig in the title? Wendy Koopa, Wave the Swallow and Dry Bones were revealed also. (Joining the others that we already knew about.) Assuming we're getting all 7 Koopalings and the Deadly 6 it looks like a pretty big roster.