How to kill Ruby Weapon

Warning: you're not supposed to get AP nor EXP from this battle with this strategy. I used Cloud through the entire battle alone.

Tools: Calculator/notepad/etc., to keep track of his HP (optional)

Enemy Skill
Mime
Knights of the Round <> HP Absorb
Hades <> Added Effect
W-item
Revive or Phoenix <> Final Attack
Double Cut (4x-Cut)
HP Plus (MASTER)
MP Plus (optional)

KotR will do 13 attacks. If dealing 9,999 damage, it will sum up to 129,987.

Dazers (paralyze)
Turbo Ether
Mirror (reflect)
Hero Drink (buff)
Elixir
Phoenix Down (optional)

* You can use W-Item glitch to get everything to 99.
* I used around 10 to 40 items in general.

Cloud Lv 99
HP: 9999
MP: 999
Omnislash

Stats (for parameter only)
Strength: 122
Dexterity: 63
Vitality: 94
Magic: 167
Spirit: 135
Luck: 29

Ultima Weapon
Fire Armlet
Ribbon

* Do not try this battle with lower stats. If possible, farm some sources.
* Any character with Limit Break that has multiple attacks will do.

Enter the battle with only one character alive and with low HP;
Ignore the tentacles (not worth it wasting time with them);
Heal yourself;
Always have Defense, Magic Defense, Haste (Big Guard) and Reflect* up.

!!! Status from Mirror takes longer to dissipate than Big Guard !!!

This strategy involves relying on your limit breaks until the boss can't use magic anymore, i.e. his MP ran out.
You can just keep healing, buffing and waiting to use your limit break, but you can also use magic hammer to drain it out of him a little faster.
You can also inflict bad status on its tentacles by using Hades (optional).
Once he can't use ultima and comet2 anymore, paralyze him so you can deal damage with attacks, knights of round and mime.
Don't forget to keep buffing and healing, since he can still get you sometimes, as well as his tentacles.