Makhmudov has some weird habits/characteristics. That head twitch of his. I reckon he takes the cake for the freakiest dude I have seen step in the ring. Any others that deserve to be on the list? I am speaking, purely visually weird dudes not things done outside the fights in their personal lives. Kooky looking dudes.
I think the 90's heavyweights top it for freakiness; Galota with his nut-punching fetish, Ibeabuchi (for well, being Ibeabuchi), and McCall for his unfortunate in ring meltdown.