If you read the transcript of Trump's July 25 phone call, he is clearly referring to the video of Biden bragging about how he force the Ukrainians to fire the prosecutor--in other words openly admitting doing all the things they falsely accuse Trump of doing and me (pressuring an ally for his own personal political and financial benefit, using blackmail and intimidation, offering US taxpayer money as a quid pro quo). For the Washington establishment, Biden's corruption is perfectly OK, but Trump should be removed from office for alluding to it in passing.
Biden is lucky that Pelosi, Kerry and others also profited from the corruption in Ukraine, or close relatives did.
Joe is slow, but maybe he got everybody on the Ukraine corruption gravy train as a way to make sure all would uniformly stand firm against charges and not turn on each other. Is he that smart? Could it be he's not as stupid as he seems?