Wrist deviation is being indirectly trained while doing calisthenics in those times you have to hold the bars in awkward angles, but what about forearm rotation muscles?
Besides arm wrestling (I don't want to break my arm doing this shit, can it be done safely?)
forearm rotation with dumbbells (they don't feel that effective)
and using a powerball exercise ball, what other ways there are to train these muscles (expecially the prone movement, that movement is really uncommon)
