Yes, and I'm hoping some Nintendo environments actaully get implemented along with a series of enemies, like the Goombas for example were good but get rid of the generic characters and add more Nintendo based ones.
As for the 3DS I believe it will have a customizable if the Wii-U version does indeed support it, I mean it wouldn't be fair just to have it Wii-U exclusive, and considering the fact that Iwata mentioned that both versions would intertwine in some way or form I believe the customizable Mii's would fit that description perfectly, meaning you could raise them in one version and simply "transfer" to the other and play with them in multiplayer modes, that's what I think anyway.