Easily solo tamed using a Mosasaurus or a Spino. The Mosasaur is a more advanced option as it is a later game option and also gives you the chance to respawn at taming site if anything goes wrong. My typical path is:
Spino to get Tuso
Tuso to get Mosa
Mosa to get more Tuso's
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.