Instructions
Save your game at the save point immediately before the Odin battle. Set up four different paradigm sets. You will need two medics; two ravagers; a medic and a ravager; and a medic and a synergist.
Move forward to trigger the cut scene and the Odin battle.
Change your paradigm to medic/synergist as soon as the battle starts. This will cause your allies to start casting Protect and Shell on your party. These are defensive spells that will lessen the damage that you take from Odin's attacks.
Switch to medic/ravager after all your party members are fully protected. This will cause your party to start attacking Odin, while keeping your squad healed at the same time.
Switch to medic/medic paradigm if any of your squad members becomes heavily injured.
Activate the ravager/ravager paradigm when Odin uses his shield maneuver.
Continue hammering Odin until your drive meter is at the maximum, then press the "Square" button to activate your special attack. This should be enough to defeat Odin.