Easiest tame on Abberration for knockouts. Use a catapult and small trap(stops them from walking, they just spin around). Hit them in the back for good torpor. Once they start to flee(not fighting), wait til they pause to hit them one more time in the back for the win.
Pretty easy to tame. Trap it in a circular form of stone Dino gates, place catapult low if catapult is high the crab will die. Then shoot it with a catapult. Cannons insta kill the crab, do not use cannons
I understand that all the previous tips submitted were useful, but just in case it was not clear, hit the TOP OF THE CRAB, it will have a special animation if you hit it in the correct spot, and will take only a small amount of boulders to tame, even a high level. (Irrelevant with Cannons)