KnightWarrior, I'm not going to make that "crazy air moves" code. Too much time involved to figure it out on the SNES, and then convert it over to the Genesis.
goldenband, this is very strange. I just tried the codes again and they worked perfectly, even in expert mode. I assume you're using the "Duel" mode?
I checked my ROM source, and there is only one ROM for Shaq-fu.
You mentioned that your cart doesn't need a master code? Very odd. Maybe you have a pirated cart or a different version that has not been dumped yet. Here is a link to the "official" Galoob master code, as well as all of the official GG codes: http://gamehacking.org/?s=v2&sys=16&gid=2929 Do any of those codes work on your cart?