Use a Managarm to tame it. It cover the requirements of dealing constant damage and keeping it in movement, plus it is faster than Acro's "tanky" state.

I figured out the easiest way to tame them! You'll need a Deinosuchus since they barely get knocked back from the Acro due to their low stance.

Get a dieno and find one then do the following instructions for an easy tame

Ride the Deino and bite the Acro until the Acro does its feeding…