While Medaka may be a quality character the same cannot be said for her brother. Maguro knows how to work on battle form and the like, but he definitely isn’t ready for a true fight. Grimmjow has the spirit of a warrior and knows how to train as well as fight. Maguro will quickly realize that he is out of his league and will likely feel the fear. I wouldn’t be surprised if he ended up throwing in the white flag right away to save himself the trouble. What he really needed was a super form. Grimmjow wins.