Holy did use his head a lot, maybe not deliberately ramming it against an opponen, but he certainly wouldn't avoid a clash and was good at getting his head down so he wouldn't be worse off. A lot of fighters are guilty of roughhouse tactics, I suppose it's just part of the game as long as you don't go to far.

As for Tyson, he was partial to rocking people with his elbows when in close, so he certainly shouldn't complain. He landed his best shots against Holyfield in the second fight, when he figured he couldn't win he looked for a way out of the beating he was about to take.