User blog comment:Sannse/Guest Blog Post - Screenshots and Chat Logs/@comment-4832646-20140627052142

Back when Creepypasta used a chat bot, it would log directly to the wiki in a project page. This doesn't counter any points, but if a wiki absolutely needs to use chat logs, that would probably be the best route to go - as well as protecting them from editing to prevent malicious edits or unnecessary changes.

That being said, it only slightly helps the credibility at best. There could always be that one admin...

As far as screenshots, I think they can be somewhat valuable; provided that they are taken under scrutiny and investigated thoroughly. But it is always a good idea to have a witness or something else affirming your story as well.