With all Titans, the battle takes place in the overworld and not in an arena. This means you are not restricted on tame limit or tame weight (or other restrictions). Use this to align your dino army prior to the fight and surround the titan. Do remember, the titan has a breath attack that applies a freeze CC, stunning dinos and dismounting the rider - do not attack in melee or suffer a blow dealing tons of damage.
I recommend bred Gigas; wild caught will not be durable enough. Apply standard boss rules like Yuty buffs, Daedon healing and good saddles for better damage and survivability. Structures do not work as it can damage even Tek, but you could take sniping position, safe from aggro, or ride the yutys and buff the Gigas yourself.
Velonosaurs do fixed damage in turret mode, only doing fully damage when ridden, not recommended due to freeze.
Could apply proportional damage effects like Fire (wyvern) or bleed (Carno, Thylo, Allo).
Watch for rival players in PVP.
This also applies to forest titan and King titan, desert titan flies so no Gigas :c
Get yourelves a army of velonasaurus and get armies of them on right and left side of the titan,put all of them on turret mode and a Yutyrannus behind the armies and put it on courage mode and they'll do enormous damage to the ice titan