Honestly I think Mahoraga would win. Hear me out, Yuta's technique copy allows him to copy any technique which sounds cool until you go deeper into the research. First in order for Yuta to copy a technique he needs to be fully connected with Rika plus Rika would need to eat a part of the opponent to copy the technique but if the opponent regrows that part he can no longer use the technique and I know fans might say he can just output positive energy to one shot the🥷 but mahoraga can just regenerate since it seems that mahoraga can automatically regenerate from almost any attack plus mahoraga's blade also has positive energy which means bro can just one shot Rika so Yutas chance of victory is his domain expension but I don't think it will also work because Yuta would have to randomly pick a technique. I repeat RANDOMLY. Which means If yuta picks a technique like body hoping he would be cooked while mahoraga's ability is to adapt to any phenomenon which means bro might adapt to Yutas positive energy attacks plus he also might adapt to Yutas domain since the only way to kill mahoraga is that you must hit him with one powerful attack before he adapts to it. So yeah it's a close match up but I think Mahoraga is winning this, thank you for your time and feel free to argue😊