Joe should win. Yu is by no doubts crazy, but anything he's done, Joe has to. Yu can adapt to faster opponents? Joe adapted to Carlos's punches which blitzed him so hard he saw them as light. He just adapted to them and started being capable of reacting to them. Yu can copy advance techniques? Joe can copy them while having massive brain damage and being nearly dead. Yu has techniques for attacking internal organs? Joe can cause organ damage with basic body blows. Joe's cross counters are a nail in the coffin since those redirect the combined force of two for Joe's punches and two of Yu's back to him. Double cross counter is double that, resulting in 8x power increase, and if he manages to land a triple cross counter, that would be a 12x power amp. Joe can outright **** with his opponents' perceptions, and has scared the shit out of people who weren't even believed to be capable of feeling any emotions. Joe has far more advanced dodging techniques, swaying in the last possible moment, allowing him to both tire out his opponent with minimum effort form himself AND be capable of throwing punches from totally unexpected angles. Finally, Joe's stamina is completely off the charts compared to Yu. While Yu has peak human endurance, Joe basically invented the tenacious shounen protagonist trope. He survived barrages from people comparable to himself designed to cripple or even kill other boxers, and went 15 full rounds with the world champion who was capable of one shotting him not so long ago. All while quite literally knocking on the death's door. Joe outlasts at worst.