Me? First, I would have the company translate Mother 3 into English and release it here in the US. Second, I would fix the online issues for Super Smash Bros. Brawl, maybe try and get the matchmaking to work faster for players who choose to play "With Anyone" mode. Also, for the Mario games, I'd say keep the main games like Super Mario Galaxy, no more spin-offs. Oh, and another thing about Super Smash Bros., I'd like to make it a game with its own original characters and story, not a game with characters crossing over.
What would you do if you were to run Nintendo?