I solo tame my squids with my mosa. If it has at least 20 k health it should be fine. Can't you a platform saddle due to glitches. Make sure mosa is on passive and follow. After you feed it swim up and the squid will let the mosa go and it will follow you up. About 8 minute feeding interval
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