The main in-house division that does the developing of games for Nintendo is EAD, but within EAD there are these studios:
Software Development Group No. 1 (or EAD 1)
Software Development Group No. 2 (EAD 2)
Software Development Group No. 3 (EAD 3)
Software Development Group No. 4 (EAD 4)
Software Development Group No. 5 (EAD 5)
Tokyo Software Development Group No. 1 (EAD Tokyo 1)
Tokyo Software Development Group No. 2 (EAD Tokyo 2)
There's also a bunch of other divisions/subsidiaries:
Monolith Soft (which has the Tokyo Software Development Studio & the Kyoto Software Development Studio)
Nintendo Software Technology
Retro Studios
Nd Cube
Intelligent Systems
Creatures Inc.
1-UP Studio
That's most of what Nintendo has first party wise, if you want to know more read the Wikipedia article on Nintendo development studios: http://en.wikipedia.org/wiki/Nintendo_development_teams
Edit: lol. Posted to late I see :P
Bets:
1. If the Wii U sells closer to 10 million LTD by 1/3/2015 I win. If it sells closer to 9.5 million LTD by 1/3/2015 OfficerRaichu15 wins (winner gets 2 weeks of avatar control)--Lost.








