Now, I don't know how many people know about this (Not enough if I'm just finding out about it), but http://www.danfornace.com/ created a gameboy style Super Smash Brothers.
The playable characters are Mario, Kirby, Link, and Pikachu. You can unlock Mega-Man and Vaporeon as well (characters that were never in the games, but an interesitng addition). The retro gameplay took some getting used with only two buttons. I'm used to having about 10 on controllers these days. But "A" is "Z" and "B" is "X" and of course the Arrow Keys are the D-Pad. My favorite part is the Smash Brothers music turned 8bit.
Anyway, check it out at http://www.supersmashland.com/ and if you already knew about this, thanks for sharing!