So, you want to tame a horror squid don't you?
Tame a army of ichthyosaur or 1 perfect tame turtle
Let the squid grab the unlucky Dino and get between it's tentacles, there is a grey "mouth".
If you have the black pearls in your 0 slot you can feed it with the E key
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