
Originally Posted by
Wolf Kanno
The same strategy pretty much works on him whether its the original or the Super version of him in the optional dungeon, the only real difference is that the Uber version of Omega has the ability to change his elemental weakness but if memory serves me correct he always starts with the same element. After that its just about levels, equips, and luck.
The strategy for the original Omega battle:
You need at either three or four characters as a Bare/Freelancer class with Mastered Ninja and Ranger and preferably a few more classes for extra oomph, you also need a high level or preferably Mastered Sorcerer/Mystic Knight so you have access to the Bolt3/Thundaga Blade ability. Ninja is important so you have innate Duel Wield and Mastered Hunter gets you access to S.Shot!/Barrage. After this you need four Flame rings which can be bought at the Mirage Town shops. If your fourth character isn't fighting, I suggest Bare/Freelancer with Time Mage and access to the Masemune so they can go first and cast Hastega on your party.
Your attackers should be Duel Wielding swords that can be affected by Mystic knight abilities and their two support skills should be the Mystic Knight ability and Barrage. In the first round have everyone cast Thundaga on their weapons and if you chose to have a support unit have them cast Hastega. Omega always starts the battle with a high powered Fire based attack that the Flame Rings will absorb. In the next round use Barrage. Basically spam Barrage and have your support character (if they don't die first) heal. Omega doesn't have much HP so he should go down in about two to three rounds but he will still be strong enough to pick off characters.
Omega Mk. II works the same way except I believe he starts off either weak to Fire or Ice, it might be something else. You could try Flare or Holy but hitting him with his actual weakness does way more damage and since he's a bit beefier he has a strong chance to take your party out if the battle lasts too long... Luckily he doesn't change his weakness terribly often so there is a strong chance you can take him down before things get really messy. Oddly enough I found some of the normal bosses in the Optional dungeon to be much nastier than Omega Mk.II and Neo Shinryuu