Go to this website www.coolrom.com and search "pokemon". Choose a game and click on it then it will take you to another page where you must scroll down until you find an icon saying "Download...
yes,there is a lot of multiplayer game like:www.ourworld.comwww.fantage.comwww.clubpenguin.comwww.runescape.comAND MORE.......p.s:you have to try ourworld.com its fun to play, belive me!!!