IMHO the battle master's maneuvers should be available to all melee combatants, but only the battle master gets the bonus damage (or gets additional bonus damage)
I'll second what Neonchameleon said! Please please do not make general monsters more complex - the existing ones are bad enough for me as a DM! Common abilities such as "Pack Tactics" are fine because I can remember the key word easily, so maybe defining up front a list of key words like that...