In order to tame this thing you need to get a turtle most preferably max level with nothing pumped into it except health and then you need to go find the giant squid and get it to latch onto the turtle then you need to swim into the tentacles of the beast and feed it black pearls until you tame it your turtle might die and probably will die but that is okay because once you have tamed this thing you will litterally be the king of the ocean as it has the power to tear mosasaurs apart with its long tentacles it can even pick up land Dino's that have wandered near the waters edge
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