While I agree this would be great, I can see ways it won't work, A. GameFreaks love to make 2 version of thier games for people to buy both, then a third wich add's either 1 new legendery and ommits a ton of pokemon or so fourth so they would'nt make money with just 1 version released and B. It would be on the Wii, as I doubt Nintendo would allow it to be on a PC and I don't own a Wii, not because I have a problem with the Wii, just the only game I want for the Wii, The Legend of Zelda: Twilight Princess I have for the Gamecube on the uber rare ( Atleast here anyway ) Camecube port of it that came out just as the Wii did and the Gamecube got scrapped, so why get a Wii.
Alternativly a fully 3D single player Pokemon game would I admit make me buy a Wii, so lets take that step first before we go MMO.