Technically Supergirl should win this, considering they're giving her pretty much the same powers as MOS. She was also strong enough to lift and maneuver a plane and tear off the front end of a tanker without meaning to. She also took on hits from a full blown kryptonian general and didn't suffer any lasting injuries.
That said, Supergirl is such a crappy fighter that I just can't give her the win here.
Originally posted by wakkawakkawakkaSpoiler:
She struggled with a human opponent who wasn't particularly fast or physically imposing...least not in comparison to the aliens she fought prior to the encounter. What I took from that is speed/fighting ability aren't really her best traits.
If you mean episode 2, she was weakened by Kryptonite levels in the training arena. Assuming you're referring to the instance where she was training with her stepsister