Every episode of Dragonball Z follows a precise formula. A new foe appears, stronger than any of the last. When confronted with a superior fighter, the protagonist will stall for several episodes whilst training, until he is finally able to summon the strength to defeat this new threat.
Superman follows a similar formula. Enemy appears. He has kryptonite. Superman runs away, then defeats him later.
The logical conclusion is that neither would ever win. Goku would be locked in perpetual training mode. If he happens to find some kryptonite, Superman will just avoid him.