Make lots of cannon balls Dododex is wrong. Must get full torp to "tame". If you can't trap it place cannon on the side of platform. Also sometimes shots will not register if titan is clipping on terrain.
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.
If you try taming these guys, tame a Quetzal first and equip it with a platform saddle. Then, put 2 storage boxes on it and a cannon. Make sure you make LOTS of cannon balls. Then, shoot the titan in the head.