You wouldn't need to prove it's beyond a shadow of a doubt ("beyond a reasonable doubt" legal standard.) That's for criminal cases. What you need here is "a preponderance of the evidence." Or in other words, is what the plaintiff saying more likely to be true.

All the math and stats show it's almost impossible for all those good breaks to happen for Biden and none to happen for Trump. Also, details on the ballots highly suggest fraud (Biden's votes violated Benford's law). We also have hundreds of people willing to swear under oath that they witnessed voter fraud, plus video evidence of Republican poll watchers being kicked out of vote tabulation rooms.

So it's more than likely that vote fraud happened here, and I think the Supreme Court will easily rule for us.