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
Just tamed a 150 on an official server. Building a trap high off the ocean floor works great just trap it and rotate out 150 tamed turtles hp pumped. Took about 2 hours with pearls for the tame. Took 50 pearls every 5-10 min. Happy taming!
OK so for those of you actually looking for tips.
1: it can eat 50 at a time so take 50 with you each time.
2: it hold mounts only for a little bit so if you can, just hop back on the turtle quickly and swim away till the next feeding
3: once you tame it beware manta s and anglers as the tuso cannot hit them while they glitch into the head of the squid. It's not that hard if you prepare to lose everything and keep trying. It's worth it once you do but you will need escorts to help with mantis and anglers such as megaladons.
Don't bother wasting sweet veg cakes and risking high level dinos. Get it to grapple your mount, feed it, swim away with your mount on passive and follow, squid will let go after a while, wait above the squids aggro level until the feeding interval is up and then go back to feed it again. Rinse and repeat until tamed. You don't need to stay in the squids grasp for the whole time, affinity won't drop whilst you wait above it.
Don't tame the squid around the world barrier or the sea floor. If you attempt to tame it, one mastercraft saddle on a 30k turtle should get you through four feedings without force feeding veggie cakes. Drive a raft over and set your turtle to follow you on Passive. Ride the turtle down with your 50 pearls and let the squid come to you, get as close to the max depth for the squid as possible. When the squid grabs your turtle, jump off spam A at its beak. Hold A to ascend quickly upwards and if you had the squid at max depth the turtle should be able to follow you back up without being grabbed again. Set a timer for 10 minutes at the surface and when the timer has about a minute left start your descent to find the squid again. Rinse and repeat. Brought three turtles using this strategy, only one left the raft and all three turtles survived.