The Dominion and Smartmatic voting machines used in many states have been programmed to switch votes, starting in the 2012 election, from Republican to Democrat. Those machines where used in the primary elections to deny Bernie Sanders the Democrat nomination over Hillary, in 2016, and probably Biden in 2020.
In many precincts ballots that were marked for Biden were scanned in over and over and over and over. In Pennsylvania the election laws were changed by the unconstitutionally state supreme courts (only the state legislature can change election law according to the United States Constitution). They changed the laws to allow ballots that came in without a signature and/or a post mark on the envelope to be counted AFTER the polls had closed. Normally (and in most other states) those ballots were thrown out.
For the first time ever, the counting all stopped around midnight after the polls had closed. It resumed around 3 or 4 am and in a matter of minutes Trump's lead in all of the sudden became Biden's lead and in some precincts it was by the exact same number of votes. Also in a few states around this time Trump showed a negative vote count. A negative vote count is not an improbability it is an impossibility because votes are additive and subtractive.
In some precincts it was reported that trucks and vans were showing up with boxes being delivered after all of the poll worker had been sent home after that 12:00am count stoppage.
Videos taken by security cameras in some of those places showed ballots being unloaded and scanned multiple times.
Some poll workers even bragged about it on camera.
Most of the polling places Republicans poll watchers were locked outside of the building and panels were put up in the windows so that no one could see inside.
I might have missed a few things but that is all I can remember.
Trump's legal team were virtually useless. In every court in every state where Trump's legal team filed a court case contesting the election the judges dismissed the cases on standing, meaning the judges just didn't want to be bothered with them. Some of those judges were Republicans.
To my knowledge no Democrat has ever put together and investigation to prove there was no voter fraud. The ONLY thing the left and their allies in the media have ever dome is just deny that there was voter fraud. No reasons, evidence, investigations have ever been sited for their denials, it is just a denial. Just empty words.