To knock this guy out be sure you are well prepared. It can only be knocked out with cannons, catapults or rockets, but don't use rockets. You need so much rockets that there's a high chance of killing the titan instead of KO it. Cannons are definitely your best bet, since they do way more torpor.
All these weapons will only do torpor if you hit it in the head. Also, when you get it stuck, it is easier to hit it in the head, but if it's stuck for too long, it will lose all of its torpor instantly, so watch out!
Once it's knockout, just put a saddle on it and it will be tamed instantly, but you do need the saddle! So if you want to tame a titanosaur, you have to be lvl 95 and make the saddle first.
The titanosaur only stays for 24 hours though, unless you change the settings on your unofficial server.
I learned that u can use a rocket turret to knock it out.all u need is to be on a medium sized cliff or a tall structure and a rocket turret on the top,and FIRE AWAY AT THE HEAD!and once its knocked out just put the saddle on it while its knocked out.I want to make sure people see this.so pls up this.