So how does he even defend himself?
Ah. You didn't get the notice, I see!
He isn't SUPPOSED to defend himself. This is easily seen by the fact that there is a concerted effort to even deny him legal representation by ensuring that anyone who works in his defense will be branded a "persona non grata" in the community, and can kiss any job opportunities goodbye if they do so.
Trump can defend himself just fine. He doesn’t need to release the content of the DoD Iran attack plans to defend why he had them, whether he declassified them or not, and how they were personal presidential papers. Seriously, do we and everyone need to know the word-for-word detail in that and other documents? The content is not on trial. It is Trump’s actions with that document that is.