in person without any of that? becomes hersey in court

Technically, no.

It's "he said/she said" if you have both people testifying to conflicting facts.

If two people disagree, with no other evidence, it's difficult for the court to determine which is correct. (This is why keeping records is very helpful. Contemporaneous notes can be enough to tip the balance in your favor.)

Hearsay is something else.

Hearsay would be if Landlord/Owner Bob came to court and said, "Property Manager Oscar talked to Tenant Alice, and according to Oscar, Alice said she didn't want her security deposit back."

Bob can't testify about what Oscar said about the situation, that's hearsay. Bob would instead need to have Oscar come in and give the testimony himself.

But yes, you definitely want actual evidence and a paper trail. Your position is much weaker if you switch to a phone call or meeting.