system
Given the following post, respond as if you're commenting on Reddit:
human
[Superheroes] How do metahumans, like Superman and Captain America, learn and practice traditional martial arts when they are not bound by the same limitations as normal humans and have practically no one to spar with?

Why do they bother with things like judo or karate?  Wonder Woman can do a quadruple backflip kick with a twist, no sweat.  Isn't repetitively practicing a *kata* that normal humans do sort of limiting her potential?  

Are there modified forms that take into account the ability to fly, stretch, phase, etc.?
gpt
In the Supergirl show Kara trains in a special room that emits very low levels of Kryptonite radiation. Not enough to harm her, but enough to bring strength down to near that of an average human, so she's able to spar with people. Other powered individuals either use similar measures to temporarily limit their power, or find other powered individuals to train with.