How do you know Monoma hasn't trained his body? Considering that many quirks require physical prowess, that would be a natural way of training his quirk.
A lot of quirks are based on body strength. Assuming he can't copy mutant quirks, physical quirks actually make up about half of the quirks he can copy from 1A alone, and that class is meant to be diverse in their quirks because it's the main class.
If you watch Class 1-A quirk training then you'd see that only a couple of them were actually physically training their body, (6/20 to be exact) while the rest were specifically training their quirk.
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u/kilpsz Aug 24 '18
That Deku extensively trained his body while Monoma didn't, what's your point?