[@Sep] Man of Steel isn't really the best thing to look at if you want rational explanations for superpowers [s]or even a good movie, I mean my feelings on the subject are pretty clear but MoS is more of a scifi film than a superhero film so don't even start trying to be logical about it[/s].

Ahem, in the case of Man of Steel, we don't know how long Zod and his posse are orbiting the Earth. 
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If they've been there a while they have had a chance to get as powerful as Clark. Plus, when Clark fights Zod, he's been running himself ragged dealing with other Kryptonians and flying over from the other side of the world so might not be operating at peak efficiency[s], not that the film tells us that, as far as we know Zod is just as powerful as Clark because...why not?[/s]. 

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