A EX Based Equipment helps, but you can do wihtout it.
You need to have Omnislash ver 5 ability equiped.
Just read Chaos, and when you see and opening or Block him, use Omnislash ver 5, as Chaos crashes down dodge ONCE backards.
then you wait midair as he after getting up will imidiatly Dash towards you. as he nears you BLOCK! after blocking repeat Omnislash ver 5 and doge away.
keep repeating the process.
Note: one the Third battle he may be a little harder, but this startegy works the same.
for the first two battles there are a few things he can do to mess up the stratagy a bit.
any HP attack, and when he dodges towards you he might do that "down lunge" attack, wich onl break your guard but does not hit you.
on the third battle he can do a BRV attack wich teleports imidiatly to your side. just try to learn and dodge and block most of his attacks and you will be OK
ill give a few pointers based on what i know.
HP attack: Condemed : or you are already with an HP atatck on his face, or you have to dodge back, as this attack pulls you in.
HP Attack: Scarlet Rain : Block All of his initial meteors and dodge the last Comet.
HP Attack: Demonsdance : everytime he teleports dodge, but only when he teleports, his last attack is when he is in a standing position with some light coming from his hands.
HP Attack : Divine Punishment : Dodge initialy, then just after the explosions stop dodge again. Or you can just be still and dodge the final atatck. Credti to this method goes to: <a href="http://www.neoseeker.com/members/o_ffxmaster_o/" target="_blank">
http://www.neoseeker.com/members/o_ffxmaster_o/</a>HP attack: Soul Of Oblivion : Just attack him before he lunches the atatck, or if you are far away just get even further as the attack has a limited range.
HP attack : Brink Of Delusion : (Chaos does this after a few sword attacks while he is Giant) As the four swords struck the stage and you are in control of you character again you imidiatly look where there is a space the lights one the ground fo not cover, then just dodge to there, if you manage to get there in time you won't be hit.
i think thats all of them.
just leanr how to read Chaos attack, he only has two Block break atatcks, being the Wall of Flame thing he shoots and the Down ward lunge he does, those were the only ones that i after defending got into a stagering position. hope that helps.
Note: this strategy was made for cloud, and may work with other characters