Just pure bullsh*t to be honest, I could've made this stuff up.
Retro's working on Star Fox U and Metroid for 3DS. They are also assisting with Mario Kart U. Mario 3D U will be out this November and combines elements from the Galaxy games and 3D Land, but isn't quite like either one. One player can play as Mario on the TV, the other as another character on the Wii U tablet for co-op and versus modes.
Nintendo has more collaborative titles coming from a pretty big Japanese studio that hasn't been shown yet.
Pretty easy to make things up.
Anyone claiming to have knowledge of internal Nintendo development or Retro projects is almost 100% full of sh*t.
Reggie probably doesn't even know what the hell EAD is doing half the time because he's not told. Leaks from Nintendo on the software side almost never (ever) happen and if they do it's at best like IGN or Nikkei reporting something like a day or two before their E3 conference.







