No, it can only play homebrew that has either been specially coded for the GBAMP, or that is under a certain filesize (i think it's 4MB) commercial games won't work.
whats the best way to play comercial roms on my ds i already have a passcard and am able to play demo's downloaded to my gbmap all but mario kaart ds
Get a M3, it's made by the same people as the the GBAMP. you can get them from http://www.divineo.net