Real Bout Fatal Fury 3 - redo all the sprites to make them even more awesome (not MOTW style awesome, just more awesomer than they are now) and keep all the characters from RB1,2,Special and put in more characters from FFS (cough* big bear *cough)
Fatal Fury Second Impact - NGPC Fatal Fury Special with ALL the characters (duck king etc.) and multiplane battle fields. Maybe some kind of extras that are super awesome like an RPG mode like in Gals Fighter or maybe NGPC link with the DC port of Real Bout 3
Fatal Fury Wild Ambition 2 - just update the graphics, battlegrounds, add new characters (and make Duck King playable as a normal character not a boss) and add galleries with art and such.
Spin Masters 2 - just make a new one, I dont care.
King of Fighters Battle Chess - reall DanAdamKOF's idea, but still how awesome would that be? You could have a certain KOF team represented chess peice versions of members of that team. Each peice that is taken by you or your opponent would show a different move or something like that. Oh mmmm.
SNK Dance Fever - or something like that. Use remixed themes and songs from all of the past fighting games, metal slug, puzzle games, baseball, etc. to make up the soundtrack. Pick a character, preferably out of some of the more musically inclined characters (Duck King, Bob, Mudman, etc.) where you have to match up the buttons to the beat. I dont think it should be like DDR, but come up with some original system that incorporates the joystick with button presses and special moves etc.
SNK vs Cacpom Chaos Pocket - speaks for itself. I wouldnt care if it was on GBA as long as it kept the NGPC style sprites.
Neo Bomberman 2 - please!