Instructions
Standard Strategy
Create a battle party with Fang, Hope, and Lightning. Set Fang's default paradigm as Saboteur, Hope's as Synergist, and Lightning's as Medic.
Create a second paradigm with Fang as a Saboteur and both Hope and Lightning as Medics. A third paradigm should have Fang as a Commando, Lightning as a Ravager and Hope as a Medic. The fourth paradigm should be Fang and Lightning as Commandos and Hope as a Ravager.
Enter a battle with the Adamantoise. Note that its main body has more than 5 million hit points, while its legs have 246,000 hit points each. Focus your initial onslaught on his legs. Switch to your fourth paradigm after Fang has cast all her debuffs on the legs, while Hope has cast all his buffs on the party.
Attack the legs until you have defeated each one and the Adamantoise will fall forward. Switch to the first paradigm and debuff the Adamantoise's body. When successful, switch back to the fourth paradigm and attack until he gets back on his feet.
Switch to the third paradigm and continue your assault with Lightning and Fang while Hope heals the party. Build up the chain meter to 500 percent with constant attacks to stagger the Adamantoise.
Return everyone to the fourth paradigm and attack. The Adamantoise should be defeated after the stagger. If not, repeat the strategy until it takes a final fall.
Change paradigms to the second one if you begin to run low on health. This will allow Lightning and Hope to heal everyone while Fang debuffs the Adamantoise.
Vanille Death Trick
Arrange your battle party so Vanille is the leader. One of your other party members should have the Sentinel role, while the other has the Medic role. An ideal party might consist of Vanille, Fang and Hope.
Set up your default paradigm with Vanille as a Saboteur, Fang as a Sentinel and Hope as a Medic.
Locate an Adamantoise on Pulse. The Adamantoise is differentiated from others of the Adaman-family by two large tusks protruding from its jaw. Engage the creature in battle.
Summon Hecatoncheir at the start of battle. This will cause the Adamantoise to fall over. Cast ̶0;Deshell̶1; on the Adamantoise until he is affected. This will cause the Adamantoise to become more susceptible to magic.
Cast ̶0;Death̶1; on the Adamantoise with Vanille while Hecatoncheir continues to attack. If the Adamantoise does not succumb to the spell before Hecatoncheir leaves, keep casting Death when Hope and Fang return while they draw attacks and keep Vanille healed.