I think I have MK2 for GB still. I beat it as Sub Zero because his specials were easy and really good. Fighting games on the GB were a mistake.
MK2 translates disturbingly well to the Game Boy IIRC.
The only fighter I ever got for my Game Boy was
Samurai Shodown, it's pretty decent, rather than try to port it they built it more around the Game Boy's abilities. (Cartoonly small characters, backgrounds you can't lose the characters in, only keeping the moves that will work and balancing for them rather than trying to fit everything, etc.) I think they went on to do a number of SNK games like it after and laid the foundations of the Neo Geo Pocket fighters. (I wasn't put off handheld fighters enough, as I later got
SFA3 for GBA, which needed World Tour mode so bad.)