In this mode in addition to the easy mode requirements, you'll want a Schemata with all four basic elements leveled to about the same stats. I couldn't find a video with a Lightning Returns image though. The return of one of the best boss themes in the series. After that, ensure you have at least four EP. Make sure either you debuff schemata or your remaining Schemata has jump on it to set up the Commando stagger. Have a full physical damage build on a single Schemata taking your Strength as high as you can get it. Again like always, Warrior's Potion and an elemental potion of any kind are useful. set up a Schemata with Deprotect and Imperil. If you want to try the easy mode, I say try because there is a fair amount of risk involved.

The first is a fairly simply all out assault the second is a more methodical approach. I recommend saving right before the battle, as there are two ways to approach it.

Definitely grab some magic and elemental resistance for this fight.