Just need a decent plesi with good saddle. Make sure to line up at the same depth of the squid. Plesi on passive and low follow. Jump off the please and stay to the left above it. Wait for the grab. Make sure it is a good grab no glitch. Swim in and feed. Swim up call follow and set 14 min timer. Repeat until tamed.
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