i played nettou kof 96 on one of those hacked cartridges. it's a pretty good game, to be honest. most people overlook it, but it had some cool combos. you could also unlock mr. karate, orochi iori and orochi leona by spamming select at the TAKARA logo screen lol.
i totally forgot that o.leona had storm bringer and this weird moon slasher DM. it is also the only KOF game where i actually like playing chizuru. it also had this slo-mo feature where if youpause the game and rapidly press select, it would progress the game frame by frame. speaking of which, i'm going to charge my GBA and play the game while i work on the wiki lol
the NGPC KOF games were also pretty darn good. i remember they even had this weird story mode thing where you could go though it and unlock moves from the character cast and you could give any character random moves of your choice.