These two went at it in the very first chapter of the series. It was certainly an effective way to introduce both characters even if it would be almost 200 chapters before R would get a serious fight. He’s definitely very strong to be sure but wouldn’t be doing a whole lot against Mori. Mori’s just on a different level. Mori Jin wins.
Ozuma is dedicated to keeping the Bit Beasts free but he would have a difficult time if R wanted to keep them sealed up. R’s got enough speed and power to easily get past any of Ozuma’s attempts to stop him. Ozuma is powerful but definitely not powerful enough in this case. His Blade would be shredded to pieces and he would be on the ground before he even realized what was happening. R (GoH) wins.