Trowa: We agree with aeris2001x2 on that. Yunalesca is a fly compared to her... And a fly even when she isn't compared to her...

Albedo: *Laughs maniacally* Truly, if you have the other version of FFX, you will see how hard it truly is...

chaos: That's enough! At least help her first!

Albedo:...

chaos: Anyhoo, she can be very easy if you follow these steps:

First, try to get most of the secret Aeons. They work very well in this battle, especially on the first form.

Next, make sure that you have levelled up like crazy. If you always stay one step ahead of the game, it'll be no sweat.

Now, in battle, I'll tell you how to defeat her. Have Yuna or someone similar to her always cure when Yunalesca drains. Auron and Tidus must be very powerful. Try to make them cut down on most of her life. Once you are done with her, the second and more annoying form will come up.

Rubedo: To take care of her, pretty much all ya gotta do NOT HEAl when she uses her Hellbiter, and when they die as a result of her healing you, just use a pheonix down. I actually felt safe with Hellbiter inflicted on me, and you will soon find out why...

Right when you defeat her, she will transform into her third and final form, and, she will use Mega-Death right of the bat. Do not think it is over though, for if your party, or most of your party is in zombie mode, nothing will happen to them. She will also inflict hellbiter in this form, along with way better curing attacks such as Regen and Curaga. Try to get Hellbiter inflicted on two people of your party, while the third one tries to keep themselves alive, because she will use Mega-Death randomly throughout the whole battle. Once you get all that, she's actually pretty easy.

chaos: Hope that helped! And be sure to train as much as possible!