They will dose him with whatever they need to to make sure he does not suffer a complete mental breakdown on the debate stage. They will install a drug pump that alternates between Xanax and Ritalin and other stimulants. When Joe is starting to ramble and go off topic, they'll hit him with a stim. When he gets angry and is about to shout gibberish, they'll hit him with the Xanax.
He will also have an earpiece disguised as a hearing aid and he will have his voice repeat in his ear what to say thanks to voice synthesizers, so he won't forget and name the handler who is speaking to him.
If he gets in office, he's going to get smothered by a pillow in his first three weeks.
They'd better hope that hearing aid has good sound quality.
Handler: "President Trump, are you defending your administration's decision to designate an overwhelmingly peaceful protest movement as terrorist?"
Biden: "President Trump, are you adrift in your mission to imprison a delegate and intermingling of jokers moving Minneapolis?"
Trump: "What?"
Biden: "Oh shit, shut up, wait, stop talking."
Moderator: "Uh excuse me, Vice President Biden..."
Biden: "Be quiet! Shit, shit, shit! You're fucking everything up! Just stand there! Don't say anything. Shit! Stop repeating everything I say! Goddamn it! Oh fuck, we are so fucked, send the Secret Service out there! Grab him, say it's a medical problem, whatever, get him off the goddamn stage!"
Drug cocktails can only go so far. He's old, frail and his mind is going, which puts him in a way worse position than Hillary in 2016. She was drug-fueled but at least she still had her mental faculties. If they're mixing uppers and downers they're walking him down a tightrope, the slightest mistake could cause him to go berserk on camera or have a stroke.
Someone with his frail constitution also needs long breaks to recover after getting doped up for an event. Remember when Joe was going to take 10 days off? Then they decided he had to visit Kenosha and he sounded like death and had a big IV bruise on his hand. If he disappears for a drug holiday, Trump needs to hammer the "Where's Joe?" message.