Bring around 6-7 or more rexs and when it lands everyone get around it and trap it. Deathworms will come and knock u back but just keep moving forward slowly so u dont get pushed out. Even when the rock golems come don't stop hitting it. Goodluck boys :)
When fighting the manticore a good strategy is bring in high level Rex's with good saddles and circle the manticore it then becomes pinned allowing you to kill it without it flying all around .... watch out for the poison it shoots at you though it will kill you off your mount like the poison wyvern ..
Just your standard passive tame but easier than most! Just have some Sand in your last hotbar slot and stand in front of him. He may try to attack you from afar but if you can make it to within a few meters, he's yours!