Even though it makes sense to bring 20 flyers, don't. Bring several Rexes, a Yuti, and a Daedon, only a few Wyverns. The boss sits on the ground for most of the fight. Bring a good shotgun to deal damage while it's in the air. Also, make sure to enable AI attacks on your wyverns so they will use their breath attacks.
A griffin is a good mount or blood wyvern when it flying you can get stuck in it it attacks you but you can hit it alot if you bring wyverns blood crystal so they can heal Tek guns doesn't work in the boss fight so shot gun if you have rhinos be careful because it breaths kill them and rhinos can't hut it when it's flying you do 1/3 or your damge I believe but blood crystal wyverns and griffins are the best and if a friend is okay he can ether spam found slam with Griff or spam breath on the blood crystal wyverns 10k hp or more recommend good amor and a good shot gun. giga no rhino maybe and kangru idk don't die because the when your flyers low go to the ground or oof by fall damge good luck and use med brews btw