I can't prove a negative since no evidence was actually presented. You could prove your idea of "plenty of evidence" by actually presenting some? I'm talking about real stuff not fantasy.
There has been literally none though, so good luck.
Also there is a pandemic with restrictions on rallies. More people showed up for anti trump rallies pre pandemic than ever showed up at a trump rally. It also doesn't even matter because what matters is the vote, and the only voting irregularities I'm aware of are a few individuals who voted multiple times for Trump, like that guy who murdered his wife then voted absentee for Trump as his dead wife