Can anyone tell me how to defeat Omega Weapon?Thanks

This is what I did:
Make sure you're Hp is at the max and junction ultima to strenght and give your party the Strength +percentage ability if they don't reach 255.
Also make sure you have every other powerfull spell junction to something. Junction death to status defense so he won't kill you with l5 Death I believe..
Anyway before you go into battle, refine the gilgamesh card into 10 Holy wars and go into battle with Zell, Quistis and Squall.. or at least one character to heal others.
When battle begins cast meltdown and aura on your strongest characters, let the third person do a holy war and have fun. Repeat the process and heal if you take any damage. Good luck :D
There are better strategies though, but holy war is usefull ;)

There are no better strategies. lol. Instead of Holywars you can start to summon a GF with more than 8000hp. This should let you survive his strongest attack (cant remember name, stupid attack though). For Light Pillar just ressurect the person to full health. Everything else you can take as long as your not at a level which is a multiple of 5. Get Squall using Renzokuken and use Zells Booya and Rush punch alternatively as they always come up one after another. With Zells attack at full (4000hp per attack) and a 12 second limit time, you can pull off at least 4 moves a second (theyre just 2 button presses) thats 4x12x4000=192,000. You can win pretty easily with a few Lionhearts and some luck :D

Spoilers.....














The Omega Battle

This is an optional battle. You do not need to defeat Omega Weapon in order to finish the game or "unlock" your party's abilities. Omega Weapon is extremely challenging and the rewards for defeating it are minimal. It's more of a test to see just how good of a player you truly are... so how good are you?
Also, after defeating Omega Weapon, anew heading, "Proof of Omega," appears in the Tutorial section of the Main Menu.

Omega Weapon HP 111,105~1,161,000 AP 250
EXP - - - -

-1
-1
-1
-1
-1
-1
-1
-1
X X X
X X X
X X X
X X X
X X
X X
X X
X X
LV HP Str Vit Mag Spr Spd Eva
1 111,105 67 61 70 121 61 0
10 202,500 113 65 128 125 61 1
20 305,500 163 70 193 131 61 1
30 408,500 213 76 255 136 61 2
40 513,000 255 81 255 142 61 2
50 618,500 255 86 255 147 61 3
60 725,500 255 92 255 153 61 3
70 832,500 255 97 255 158 61 4
80 941,000 255 102 255 164 61 4
90 1,050,500 255 108 255 169 61 5
100 1,161,000 255 113 255 175 61 5


Level Draw
1~19 Flare Holy Meteor Ultima
20~29 Flare Holy Meteor Ultima
30~100 Flare Holy Meteor Ultima
Drop Card Mod Card Mod (Rare)
- - -
LV 1~19 LV 20~29 LV 30~100
- - -
Strat:
This is a tough battle. You probably will not live through it. Limit breaks and Eden work well here. Make sure you have Holy Wars.
Locations:
Ultimecia Castle (Chapel)

Description:
Stronger than Ultima Weapon, Omega Weapon is the strongest monster. It is bad luck to run into this monster.

Level Rate: 255/256
178/256 51/256 15/256 12/256
1~19 Three Stars Three Stars Three Stars Three Stars
20~29 Three Stars Three Stars Three Stars Three Stars
30~100 Three Stars Three Stars Three Stars Three Stars

Level Rate: 32/256
178/256 51/256 15/256 12/256
1~19
20~29
30~100



There's another switch point near the fountain. Leave your main party at the switch point, and take control of your party. Exit the Front Foyer via the door on the upper-right side of the room. There's a large bell in the ceiling of the very next room. To summon Omega Weapon, you must ring the bell. To do so, have the leader of your secondary party pull the rope at the base of the stairs.

Upon doing so, a timer will appear in the corner of the screen. The timing indicates the time you have to find Omega Weapon and to initiate the battle. Quickly run your secondary party to the switch point in the same room and take control of your main party. Then run to the Chapel where the organ is to find the hulking Omega Weapon. To initiate combat, simply run into the Boss.


Preparations for Battle
This is no ordinary battle, so you must plan ahead of time. Before you ring the bell, take some time to refine some items from cards, rearrange your spells and items, upgrade your weapons, and make sure everyone is healthy.

Use your Card Mod ability to efine 100 Megalixirs from the Bahamut card, 100 LuvLuvGs from teh Chubby Chocobo card, and 10 Holy Wars from the Gilgamesh card. Move the Megalixirs and Holy Wars to the front of your item inventory, along with any Mega Phoenixes in your inventory. Use the 100 LuvLuvGs on the three characters in your main party so that each character is at full compatibility (1000) with each of the GFs he/she is equipped with. You'll need your GFs to arrive quickly in the upcoming battle.

Examining your party's Junctions. Junction 100 Death spells to each party member's Stat-Def. Omega Weapon uses a Level 5 Death spell that can wipe out the entire party in a single shot, so be prepared for it. Check your party's Command Abilities. Make sure everyone can summon GFs and draw magic. Additionally, have at least two magic users, two people who can use items, and you may want to equip the Recover and Revive abilities.

Also, check your Character ABilities and remove any Bonus or Mug abilities. Replace these with abilities that increase your character's vital statistics with a focus on Speed, Strength, and Magic. You may also want to equip abilities like Auto-Potion or Auto-Haste, but stay away from equipping Auto-Reflect.

Make sure Squall has this ultimate weapon, Lion Heart. This enables him to perform the Lion Heart Limit Break, which can cause close to 100,000 points of damage to Omega Weapon. If Zell and Irvine are in your party, upgrade their weapons as well because they will use them in their Limit Breaks. The female characters probably won't use their weapons throughout the entire battle, so upgrading is not necessary.

\ Check your GFs. Make sure Cerberus, Eden, and Doomtrain are all Junctioned to a character taking part in the battle. Also, Junction each GF on a different character so that you can cast all three simultaneously. Also, make sure Eden IS NOT junctioned to Squall; he'll have other things to do besides summoning GFs.

Make sure that you have a small supply of Aura spells (at least 18) in the Magic inventory of a character equipped with the Magic Command Ability. You should also have a supply of Full-Life and Curaga spells just in case you need them.

That should do it! If you find you've forgotten something once you enter the battle, you can always try to regroup for a second assault.


An Epic Battle
Let me start off by recommending a party. AI like Zell, Rinoa, and Squall for this battle. Give Zell Doomtrain and the Magic Command. Give Rinoa Eden and the Revive Command. Give Squall Cerberus and the Magic Command and Item Command abilities. Granted, a lot more goes into this setup, but these are the only specifics. You don't have to set up your party in this fashion, it just happens to be my personal favorite.

As the battle begins, quickly summon Doomtrain, Ceberus, and Eden, however, DO NOT boost Doomtrain. Doing so will heal the Boss, but it will also weaken its defenses. This will enable you to cause double the damage using physical attacks, such as Squall's Limit Break. Cerberus will set up your spell casters with Double and Triple, which you'll use next. Eden will deal out the first dose of major damage. Attempt to boos Eden as high as possible to inflict maximum damage.

After the GFs do their work, have a spell caster use Aura on each party member, or at least the two characters without Eden. Now the two characters not using Eden will be able to dominate Omega Weapon with repeated Limit Breaks. With any luck, Squall will use the Lion Heart Limit Break several times in a row.

With Aura in place, have the character equipped with the Item Command Ability use Holy War on the party. This will make everyone temporarily invincible. It's important to do this after Aura is cast, because Holy War blocks magic. Without the Aura spell, you'll need to rely more on GFs and strong magic.

If you followed my suggestions, Rinoa will constantly summon Eden after using Holy War Squall and Zell will begin using their Limit Breaks.

Everyone should keep this up until either the Holy War or Aura spell wears off. Aura will typically end before the Holy War effect. During the remaining seconds of the Holy War effect, you may want to stock up on Ultima, Holy, Flare, and Meteor spells from Omega Weapon. This is your best shot to get a full 100 Ultimas.

When the effect of Holy War ends, quickly recast Aura on everyone and use another Holy War. Follow the same tactics and continue recasting any time you need to. This battle will take a long time, however, if you use this strategy you won't lose unless something goes horribly wrong. Like if Holy War wears off at the same time Omega Weapon uses his Tetra Break attack that will kill a summoning GF and the character summoning. Instant Game Over!

For defeating Omega Weapon, you receive a Three Stars. Not much of a prize for such a tough fight, but the chance to stock up on strong spells is well worth the effort.