Bring something that can kill a tuso in addition to your tank. These things are notorious for bugging out; when it does, you won't be able to feed it, and it won't let go of your turtle or mosa until it the tame is dead. Lost a 36k hp 560 melee mosa this way.
Use a Mosa to tame this beast. Let the Mosa get grabbed wait a couple seconds get off feed it black pearls. Have your mosa on follow lowest, swim a bit away from the Tuso after feeding it, when the Tuso lets go the Mosa will swim to you. Repeat until Tuso it tamed. Super easy!
You need two people, one for feeding the black pearls and the other to feed the turtle that is in the grasp of the Tusoteuthis, with sweet vegetable cake for the health and to feed it stimulates berries as well