Have 2 people. One person carry the sabertooth with the argy or if you want, quetz/wyvern. The other person tranqs it. The saber will stay still, allowing head shots with the right positions, both saber and the shooter. The saber will fall from the from being carried to the ground when unconscious. This way, you can tame the sabertooth in your base or where ever you want/need.
Easily knocked out when you use a bloa. When stuck shoot in head while you can and itll go down quickly. Tranq darts make the process quicker, but arrows will do the job just fine. They can be picked up and dropped into safe taming cages by argies to make this easy tame all the more easy.
When I was taming my sabertooth on mobile. I went to dead island, lured a sabertooth to the small island beneath the main dead island (sitting on a pelargonis), jumped down to the ground and started shooting it with my crossbow and tranq arrows. When it was down I placed wooden spiked walls around me, my pelargonis and the sabertooth. Then I just putted like 100 raw meat (I always have too much meat just in case) in it and fed it narcotic when needed. When it was tamed I got it into my raft and sailed home. Really safe taming.