In Motion, the PF and SF take more shots than they do in any other Outside Based Offense. So you want to make sure your PF and SF have good shooting skills. Also, having good shooting all round the board can really help your chances of getting an amazing mismatch. For example, I played a game in which I played an SG at SF and played Motion. The opponent's SF was a PF who didn't have very good OD and he played M2M. I absolutely dominated that matchup and went on to win.
People say in Motion JR is not that important, because there are a lot of mid range shots and not as many 3 point attempts as RnG or Princeton.
Also, Driving plays a factor in Motion. You'd want your guards and SF to have good driving. Apart from that, rebounding is always beneficial, I can't think of a situation where it MORE essential. Guards having Inside Scoring...hm... I guess it makes sense, because good driving would inevitably lead to a few Inside Shots.
But I don't think C plays a major role at all in Motion. He hardly takes 4-5 shots in the whole match. Outside Scoring for PF,yes, but not for C IMO.
Hope I helped!
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