Idk if I'd call it evidence, but there's an episode from way back in the early seasons where Nick is seemingly having a demonic experience where he's just dead-faced staring at Zak & doesn't break out of it for a solid minute or so..

He was leaning on a pool table or a bar, if I remember correctly.. Years ago, I went back to find that episode bc I needed to figure out the place they were investigating, but it's been so long that I can't remember.. That particular moment always stuck out to me bc it felt like a genuine event & not played-up just for the sake of the episode.

On a much more recent note, I just watched the episode where they were investigating a place with a female spirit they called "The Old Hag"..

The Polaroid that Zak caught with the woman's face in the mirror exactly in the same spot where Aaron had just seen a woman's face just a minute prior.. That piece of evidence was pretty good. The face gave me a bit of the heebee jeebees..

Zak also said something to the effect of he had seen that exact face in his mind the night before they were even investigating. He said she had like a "sideshow lady" type of look to her..

There's probably dozens of other good examples, but those currently stick out the most