To many to list. Just cuz dude goes tooth and nail with Manny doesn't mean he wouldn't be easy work for other fighters i.e. Floyd.
It is not just Manny. Floyd did fight him and he was never close to stopping him. Like I mentioned earlier the time he did open up with JMM he got hit with a 3 punch combo and then he went back to 1-2s all the way to the 12th round.
It's a miniscule puncher's chance, but it's still there. Hamed was one of the hardest punchers ever at 126. He could put almost anyone out at that weight if he caught them flush once/a few times, including JMM (JMM is too good of a technician to get caught very often, but there's always a chance he does, and if he does get caught, it'd be very bad for JMM.) Also, as turbotime mentioned, Mosley at 135 has a good chance. He was huge, fast, and powerful at the weight.
Only Flaco and even he is far from certain to do it. Azumah Nelson over 15 rounds is a slight possibilty.But Juanma could well survive against both. I think Chava wins but not by stoppage.
Agreed, I think out of JMM, Barrera, and Morales, Prime Naz would have had the best chance with Morales, mostly because Morales would almost certainly trade with him.
I think Sandy Saddler at Featherweight could. He had 103 KO's. Henry Armstrong at any weight classes i'd favour to KO Juan. Roberto Duran at 135 too.