The Super Smash Bros. series has made appearances on the Nintendo 64, GameCube, and Wii, but Nintendo hasn't yet brought it to a portable system. Nintendo fan Dan Fornace took matters into his own hands and made Super Smash Land for Game Boy. Sort of. It definitely looks like a Game Boy game, but you play it on your PC.
Super Smash Land is available to download for free. No online multiplayer, though.
Check out the launch trailer:
Download from http://www.supersmashland.com/