Problem is, Nintendo's characters don't fit with each others. Square Enix' do.
What's the only game that most of Nintendo's characters have appeared in together? A fighting game. They kill each other.
That's pretty much the only genre Nintendo's characters could fit together in.
And that's one of the few genres that Disney would just be crap in.
A "Mickey And Mario" (Like Mario & Sonic) could work. Something like that anyway. I think you need to do Mario alone, rather than Nintendo overall.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS