Cardio. Become a cardio freak and maybe he can hang with Cain... That's it folks otherwise no one beats Cain right now 
It's Cain not JDS imo
I can't see anyone beating Cain for a long time, this is why I think Nelson has the best shot, I don't think anyone else can take him out with one clean shot. Nelson would have to land in the first 30 seconds mind you, lol. JDS landed a hell of a punch straight out of the blocks and it barely fazed Cain.