They have half a dozen in-house teams and more then half a dozen second party development teams, not to mention several of their usual contractors and occassional 3rd party collaborations like with the upcoming Smash Bros, their normal SEGA team up for the Olympic games.
The fact is, Nintendo's own quality control is probably the biggest deterrent for games then not having studios. Anyone need only look at the various developers that produced Nintendo games over the years to know that Nintendo can find and nurture smaller developers into producing pretty good games, they just have to take the time to do so. The Wii seems to be the first era this wasn't the case but if you look at Nintendo's Japan releases, it shows that they worked with a number of developers but for whatever reason they didn't try to bring more then a third of them to the Western regions without having their arms twisted or it being something more casual.
Edit: Heck the main flaw I suspect they are having with the Wii U isn't so much the development teams, it is that Nintendo really hadn't prepped their own teams for the difference in trying to get HD visuals out of their games. Despite the fact that the Wii seemed to have been abandoned by the Nintendo main dev teams after Skyward Sword, I suspect that Nintendo placed more focus on the teams learning how to make the most of the 3DS until they realized too late how they bombed the Wii U.
