Titanic, nobody can describe the power that this Digimon held. Merely by itself it had the power to destroy entire mountains, and was powerful enough it was considered by some to be a deity, besides the fact Titanic was incredibly huge for even Machine Digimon standards, big enough for the already large SuperMechadramon to use Titanic as a war chariot, easily being able to carry around SuperMechadramon and it's additional Mechadramon attachments with ease as they completely demolish any opponent in their paths. It's role and usage in the series is a complete tribute to the Carrier Zord Titanus from Power Rangers, even being combined with two different Digimon previously not meant to combine with a TitaniumMechadramon.
Digimon: Bursting Cries/Digimon: Aftermath
Though appearing earlier before Zero Finale, Titanic's first major role is it's part in the destruction of ZeroDragoramon, where it is summoned and DigiXrosed with all the other Mechadramons, forming UltraMechadramon Superior Mode in the process. Out of the Mechadramons, Titanic was the only one of them that was sentient, though it never spoke actual English at all. It's usage in the series overall is almost identical to the Zord Titanus from which it is a homage to. While the other Mechadramons were destroyed, Titanic survived due to it's level it was by itself compared to the rest of the Mechadramons.
When Stellerdramon and Photondramon were on a rampage 12 years later, fusing into the mighty Fusiondramon, more power was obviously needed to destroy it. The Grand One used the surprise reveal that Titanic still lived and brought him into the new universe to destroy Fusiondramon. However, Titanic was not powerful enough by itself, and needing more power, The Grand One decided to break his own rules he set by making Shoutmon X7 capable of Xrossing with Titanic, and created a new form that demolished Fusiondramon and the threat was eliminated.
In the finale of Aftermath, when every single tamer raids against Gaiamon, who is possessed by Dragoramon's spirit, after several crucial parts of Gaiamon's armor destroyed, leaving plenty of gabs for a final assault, the currently to be revealed fused form of Puffy, Mysteros, Charming, Killer, Gear, Jim, and Megaton combining with Titanic in what would be it's last battle, Titanic and it's third user in it's lifetime deconstruct Gaiamon and successfully destroy it, leaving Dragoramon's spirit exposed as Titanic lets itself by possessed after it ejects the combined Digimon it's fused with and vaporizes both itself and Dragoramon's spirit with Gaia Genesis Cannon, permanently destroying Dragoramon once for all. All of the remaining power from both Digimon went towards Organidramon's power, so that The Grand One wouldn't have to create more Digimon potentially more destructive than his previous batch.