Acquiring the power of Superman would make all other training irrelevant. Consider Judo, which uses gravity to facilitate falls. You can't trip someone who can fly, no matter how many belts you have. The best boxer in the world would be just as mowed down by a machine gun as a couch potato would be. Also, Brandon Routh's Superman took a bullet in the eye and didn't blink, so even vulnerable spots on a non-super become insignificant at Superman levels of powers.
At that level of power, the power level is the only significant thing, barring (in this case) access to Kryptonite. As others have mentioned, Superman has higher power levels than does Zod due to his longer exposure to the Sun and the Earth's atmosphere. Superman, therefore, wins through power-imbalance attrition, as is shown in the movie.