A Pokémon MMO for the Wii U would be great idea for Nintendo. I don't think it would necessarily diminish the importance of the traditional handheld games, either. The MMO would just be a way for Nintendo to expand the world of Pokémon, which I think we would all agree is necessary. Plus, the Wii U could use a game to entice people who have a 3DS/2DS to purchase one. A Pokémon MMO would be perfect for that, considering a lot of people only buy 3DS/2DS's for the Pokémon games anyway.