Namely, pity. "Joe has given a lot of years to the people of Delaware and answered the call to run for president when he should have been retired, on the beach. Now we all have to watch his health decline before our eyes in the most demanding job on the planet. This isn't fair to Joe and it isn't necessary. And, look, Joe thinks what he's doing is best for the country, but it's not. Not economically, not in terms of immigration, in terms of crime, and not in keeping a peaceful world. He isn't up to it, but that isn't his fault. He needs to rest and reflect on his career."
Competition is about finding edges and exploiting advantages. The Biden team will not anticipate pity and anything conciliatory or complimentary. They haven't programmed Joe for that.
The other thing I don't think Trump and Company are sophisticated enough to do is to use the proper bait that will force Joe to use his failing memory, Trump needs to end some of his remarks with statements that bait Biden into recounting things that have happened, including things in chronology. The drugs won't improve Joe's ability to recall things precisely or to be able to place things in proper chronology.