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 roar, then dismount quickly and feed the biotoxin. Get back on the Deino and repeat. You'll be tanking the Acro's attacks so watch your Deino's health. When the Acro does its stomp or fake roar, stay on the Deino and you'll only get knocked back a tiny amount. You can easily knock a max one out in a couple of minutes this way.