Would prefer 15 rounds = Calzaghe, Froch, Mayweather and Hatton. Would struggle with 15 rounds = Pascal, Groves, Bute and Canelo.
Can't see the super heavyweights adapting well to 15 rounds that added mass does catch up with you, someone like an AJ or even Lewis big tough guys would gas quite hard late in the fight
Joshua doesn't appear to be a 15 round fighter to me as are many of todays lumbering heavyweights , but #1 who couldn't handle 15 rounds ----- Canelo Alvarez
I can see Pacquiao, JMM, Trinidad, Mayweather, Froch, Calzaghe, Chocolatito, Inoue, Crawford, Bivol, Usyk being able to do well in 15 rounds. Canelo, AJ, Zhang, Jermain Taylor, Pascal, Sanders, Kovalev, Judah wouldn't be able to handle going 15 rounds.
I think all of JCC’s title fights were 12 rounds but he was a 15 round fighter through and through. Had he picked up the WBA junior lightweight title rather than the WBC version, I’m sure he’d have shown it.
Foreman is a possible 15 rounder during his comeback years. He knew how to conserve stamina as much as possible.
Hopkins during his 160 prime and even for a short while after he released the weight shackles/drainage and slipped up higher would be brilliant over 15 rounds.