I found the best way to tame aggressive and more dangerous creatures is to use Tapejara (saddle acquired at level 55). They can land on high and vertical surfaces while still allowing you to shoot. If the tame is not close enough to the ledge, I suggest shooting it or Argo-ing it to follow you. This method helped a lot i was able to easily tame a spino and Rex.
I recommend using a scorpion to tame it, pump all levels into health on the scorpion. Then just attack the Rex but with 10 to 20 seconds in between hits, DO NOT pump anything into dm. Also this is what I use to tame literally everything, and it doesn’t even cost anything. Pls put this up in chat for everyone to go “oh that’s not a bad idea” 👌😄👍
If you use the bear trap strategy which is if you lead it into a Dino gateway that is shaped in a triangle and with a bear trap in the middle (Large Beartrap) and when it is stuck you must put a dinogate behind it to trap it and then knock out.