I don't think there is gonna be a debate, if there is, Donald will run from the stage with blood running out of his asshole after Joe rips him an oversized one. Next day he will say Joe was all hyped up on drugs like a crazy person, while he tells us not to believe what we saw, but a new reality.
I've seen Joe in action in the past, he's still got it in him, the stutter disappears when he gets pissed, Joe can rip a strip off someone like no one else can, he has a tongue like a razor if moved to use it. Most people become articulate when pissed, all the shyness disappears as they lay it on the line, Joe like most Americans has much to be pissed about. I figure Joe should piss Donald off so much he snowflakes out and storms off the stage in a rage. I also figure calling him a moron and saying he has a professionally assessed IQ 78 that he demonstrates daily, would be highly effective, if you want to piss off a pretentious moron, call him a moron. The fact he is a liar is well known and won't have much impact, but calling him a dummy and a loser will get the desired effect.
Once Joe drives Donald from the stage and humiliates him on the way out the door, he owns the venue and should immediately forget Donald and focus on the plan for recovery and the future. Donald is very reactive and if you know his triggers you can play him like a fish, he needs to get his ego through the moment and will do anything to do it, overwhelm him, shock and awe, make panic and retreat his mode of survival. Speak the outrage of the American people, be their voice of justice and accountability until he's gone from the venue, only Trump's hardcore base could be offended. Joe wouldn't lose an honest vote by speaking the simple truth to Donald's face and calling him what he is and what his own cabinet has called him, a moron, then proceed to prove it.