A fair fight guide line should be looked at like a UFC fight.
You can do anything but pull hair, gouging eyes, headbut, and a kick to the groin.
All else is fair. If you feel the need to do those other things then you shouldn’t be fighting in the first place.
Like BuickGN said fight like a man and if that means you get your ass kicked then take it like a man.
Just my 2cents