to fight mike tyson from the opening screen go to code and enter 007-373-5963
This code puts you against Super Macho Man at 97-0 and I think that it also gives you 97 KOs. That way if you beat Macho Man and Mike Tyson both by KO, then your record will be 99-0 with 99 KOs.
After the 1st or 2nd rounds over, when the doctor talks to you, press the "select" button rapidly before the 2nd or 3rd round comes up, you will regain your health meter.
TKO of Super Macho Man in 1 Round:
I've found 2 ways to do this. If you don't allow yourself to be hit at all by Super Macho Man, then you can TKO him by straight punches without a star. If you do get hit, you will probably need a star. After obtaining a star, it may be helpful to use it on the third knockdown.