Give those two one year to train full-time for each other's sport. Who would be more competitive? Keep in mind that Joshua is not Floyd. He's a knockout artist in his prime, and wouldn't bother waiting for Stipe to tire himself out. He would go straight for the kill in a boxing ring. Same could be said for Stipe. My best guess is that he would immediately shoot for a takedown, or throw leg kicks to try to finish the fight ASAP.