Gamma manticore pretty easy if you know what you're doing, 10 rexes 20k health and at least 500% attack, a good yuty and maybe a pig

Use at least 10 rexes and a yuty, rush it with minimum 2 people

Do NOT bring Wyverns. They have really bad Torpor, and the Manticore will rarely land. Bring your standard boss dinos like Rex, Yutys, and Pigs. Also try to bring a gas mask as it protects you from the Manticores torpor attack. Try to avoid the Golems as it'll be a waste of time. When the Manticore lands whistle "attack my target" on the Manticore and then when it flies away whistle them away from it and repeat. Avoid the torpor attacks with your Yuty.

High level lighting wyverns at least over LVL 200 just need health and melee also turn off lighting attack as it will kill your own dinos

Use rexs for manticore and you’ll be fine