Nintendo doesn't need to, shouldn't, and I'd even go so far as to say can't partner with another company. They function by being control freaks. They were control freaks with the NES and single handedly saved the entire industry. They were control freaks with the N64, which is the reason Mario 64 turned out the way it did and set all the ground rules for almost every 3D game to follow. There's no way in hell it would have worked on the PSX. Not without massive load times and quite a bit of "Okay, there's the platform. Now jump and... Hey? It moved! *dies*". And the only reason the Wiimote exists at all is because they were control freaks about that too. If they had been tied to Sony or MS or another technology company only interested in taking over the industry in order to sell everything other than games they would have been laughed out of their offices and told to go make a regular controller. Sure they want to take over the living room and all but they don't want people to actually REALIZE that. A remote control shaped controller... Hello! Can you say 'obvious'?
Why can't these companies just be strait forward about their evil intentions?