Now these guys are hard, even harder than Sephiroth himself and its because they have about 1,000,000 HP each! There are some basic equipment you need to beat them. First you need the Knights of the Round summon materia. You can get it by breeding a Gold chocobo and using it to get up to the island at the top right part of the map, go back to my Chocobo breeding section when I get one to learn how to breed a gold chocobo. Next make sure to have a good supply of HP and MP plus materias, you can get them at Red XIII's town, Cosmo Canyon. You need these because you want your groups HP at around 9000 each and the MP at around 950. Get them early in the game and build them up so you can get alot of HP or MP out of one, you want as little of these materias equiped as possible when you fight the Weapons. Make sure to have a good magic plus materia also, when you equip it to Cloud (he's going to be the main character in the fights.) he should have about 230 magic power (check on the status screen). A very important materia also is HP absorb,make sure you have this! It should be at a fairly high AP level also. You can get this materia in Yuffies town Wutai in the room with all the cats. Other materia you need are Quadra Magic (Blue materia), Mimic (yellow materia). You can get both of these in materia caves that you can get to by using the black chocobo. You also need Final attack (Blue materia) which you should be able to get if you get both the Omnislash and the W-Summon(which you also need) at the Golden Saucer battle arena, this could get very boring but you have to do it. after you do it fly around ( you should be towards the end of cd 2) and fight the Ultimate Weapon that is flying around, after you beat him and get Clouds Ultimate Weapon from him go back to the Golden Saucer and fight the special fight that is offerd to you, win it and you will have the final attack materia. Another good thing that you should have is the Big Guard enemy skill that you can get from the beach plugs on the beachs by Costa del Sol. And get some Sprint shoes from the Chocobo races. Some recommended items are the Mystile armor, Ultima Weapon ( you get this from the Ultimate Weapon you fight ) and a ribbon, you also want a Phoenix summon and a Bahamut ZERO or another strong summon. You must have a good supply of Turbo Ethers or Elixers (Elixers preffered).
Heres a list of all of the above:
1. Knights of the Round summon materia
2. enough HP plus materias to get your characters up to about 9000 HP
3. enogh MP plus materias to get Cloud up to 950 and another at about 650
4. W-Summon materia
5. Final Attack materia
6. Magic plus materia
7. Sprint Shoes
8. Enemy skill materia with Big Guard on it
9. HP absorb materia
10. Mimic materia
11. Elixers and/or Turbo Ethers
13. Mystile Armor (highly recommended)
14. Ultima Weapon
15. Quadra Magic materia
16. Bahamut ZERO or strong summon materia
17. Phoenix summon materia
One more thing you should have all of the characters in you party at around level 60.
Ruby Weapon is the easier of the two weapons and you should probably fight him first.
Here's a list of things you need for Ruby Weapon:
1. Mystile armor
2. Enhance Sword or Ultimate Weapon
4. HP Absorb linked with Knights of the Round
7. Quadra Magic linked with Bahamut ZERO (or what ever summon you want)
8. Magic Plus
9. Final Attack linked with Phoenix
10. Enough HP and MP Plus' to put Cloud at 9999 HP and 950 MP (you need all the HP and MP you can get
11. Enemy Skill with Big Guard
12. Sprint Shoes
Equip Cloud with the Mystile armor, Enhance Sword or Ultimate Weapon and Ribbon. Now for equipping him with Materia. Equip him with the HP Absorb linked with Knights of the Round, Magic Plus (make sure you have about 220-250 magic power), W-Summon, Mimic, Quadra Magic linked with Bahamut ZERO and Final Attack linked with Phoenix (this is just a precaution). Use whatever slots you have left with HP and MP Plus'. Cloud is going to be the only character you are going to use. Next, equip another member of your party with the Sprint Shoes and the Enemy Skill. The last member is going to have no use in this battle. You might want to have Turbo Ethers or Elixirs around just in case.
Fighting the Battle:
Start off the battle by having the person with the Big Guard Enemy Skill cast Big Guard. Make sure you do this very fast and before anything or anybody has a chance to do anything. This will help Cloud a lot. Make sure that you save the game before the battle because the Ruby Weapon might suck Cloud in, but don't worry, just keep doing the battle until Cloud isn't sucked down. Right after Big Guard is cast have Cloud cast Bahamut ZERO with W-summon. This may or may not do any damage, its just to provoke Ruby Weapon to stick is tentacles out behind you. It does not matter if you other members get sucked down, just so long as Cloud is alive. When you see his tentacles behind you cast W-Summon Knights of the Round (if your running low on MP use an Elixir or Turbo Ether.) at the tentacles, (it wont be cast two times if its at level one but it doesn't matter, the main thing is killing the tentacles) this will kill them thanks to the high magic power you have due to the Magic Plus materia. Plus you will get healed because of the HP Absorb. Now just mimic every turn and Knights of the Round will be cast twice even though it could only be cast once before! And because you are mimicking it won't cost any MP! Just keep doing this each turn and you will eventually kill him. He might try to use Comet2 and other spells but thanks to the Mystile armor it will usually miss. When you beat him you get the Dessert Rose.
Here are the items required for beating the Emerald Weapon:
1. Final Attack at level 2
2. Phoenix at level 2
3. Knights of The Round at level 2 (You use the AP you get from Ruby to get this up)
4. HP Absorb
5. Quadra Magic at level 2
6. Bahamut ZERO at level 2
7. Enough HP and MP Plus's to get 2 characters at the highest MP and HP levels possible
9. 2 Magic Plus's, one at master level, the other at level one or two
10. Two Sprint Shoes
12. Elixirs and Turbo Ethers
13. Good Armor and Good Weapons
14. Underwater Materia that you can get from the guy at Kalm (Morph the Ghost Ship enemy to get the Guidebook and exchange it for the underwater materia)
You need someone to have the underwater materia because the battle is probably going to take more than twenty minutes. First choose the person you want to hold the underwater materia, this person will have no part in the actual battle, so do not equip him with anything except the Underwater materia. Next equip Cloud, Give him Final Attack linked with Phoenix, Mimic, Sprint Shoes, Magic Plus (get his magic power as high as you can.), and fill the remaining slots with HP and MP Plus's (make sure his HP is higher than 9000 and his MP around 600.) For the last character equip this: Quadra Magic linked with Bahamut ZERO or strong summon (Bahamut ZERO recommended), HP Absorb linked with Knights of the Round, W-Summon, Sprint Shoes, the other Magic Plus, and enough MP Plus's to get the characters MP around 800 to 900, make sure the HP is fairly high too.
Fighting the battle:
Start by casting W-Summon using Bahamut ZERO and KOR, right after that have Cloud mimic it. This is the start of a combo, if you do this right you will see Bahamut ZERO cast 4 times and KOR cast once. After this just keep mimicking with Cloud, skipping every ones turn. If all the other people die don't worry, you just want Cloud alive at this point. So after awhile of Bahamut ZERO's and KOR's Emerald Weapon will probably try to kill you with Aire Tam Storm, if he does your Phoenix will revive your group, which in that case you will have to start the combo over again but eventually you will kill him. You get the Earth Harp from him, which you can exchange with the guy at Kalm for three Master Materia's
Note: If your KOR is a level two you can, instead of casting Bahamut ZERO, cast KOR twice, which will make the battle faster.