The case with Hillary is the worst. She deliberately violated a whole raft of federal laws in setting up her private server. She allowed classified documents to be put on it. She and others with access copied files including classified information off that server and put it on thumb drives, etc. One of her lawyers had copies (plural) in his office for example. She wasn't President at the time either.
Biden is an idiot. I believe in his case they just were incidental, but there was a pretty big quantity and he let them get spread all over the place. Stupid isn't a defense, and Biden clearly wasn't President when the documents were moved.
Pence should have clearly known better and wasn't a President so he couldn't declassify things. He apparently had some classified stuff mixed in his files on leaving office. That was sloppy but at least he had control of the material unlike Biden and Hillary.
Trump knowing took the documents, but was President and technically could declassify them. This presents a grey zone. Sure, Trump shouldn't have bothered with these documents as they were classified, but he did. He should have declassified them by a proper means rather than just waving his hand and thinking they're now declassified. I'd say of the four, Trump is the hardest to prosecute for this potential crime.
Another unknown is Obama. Hundreds of thousands of pages of documents left with him and no one has gone through them. So he's potentially yet another case of this.
