On mobile single player I used about 12 behemoth gateways to make a large pen. Lure titan into pen, place last gateway and tamed with Quetzel/cannon technique. Just go past render distance after each shot and come back and repeat. This was tedious but better than it drowning when it flees.
You hit it with cannons on a quetzal. Go for it’s head. It’s torpor won’t drain either so take your time. They can’t eat just stuff a platform saddle on the titan once KO’ed. You use daedons to heal it when it’s food level is low.