Are there any contemporary boxers of note who fight out of the cross guard? By "fighting out " I mean using it as the standard guard, not sporadically. Also, how do you block a left hook while using the cross arm guard?
Ken Norton and Gene Fullmer both used the guard quite well. Fullmer in particular had a very weird reverse cross armed guard. Archie Moore also used the crab guard quite well, probably the best of anyone.
If you stand squared up with your right arm crossing your chest then it is almost impossible to stop a left hook from crashing into your temple. Moore used his elbow to stop that hook to his temple. I don't know how anyone could raise his elbow quickly enough to block a fast lead left to the head.
Chad Dawson used it sometimes. He didn't use it consistent enough though. 90's Foreman and Holyfield would be the best contemporary examples of using it correctly. Very difficult to pull off.
I use this defence when my wife steams me when I come home really late, maybe 3am, too drunk and have said I'll be home by 8pm It confuses her, she's a southpaw so it helps me..
Terrible Tim used to continuously move his right glove across his face, from the front (to catch jabs) to his right ear (intercept hooks).