She dosen't like Holy attacks.

Just a quick note : To avoid her Mega-Death attack , If you simply keep the Zombie status on all characters at all times, Mega-Death will miss everytime. In this battle, there really isn't a downside to keeping Zombie on, Unless Yunalesca casts Regen on a character Just get Yuna to dispel it, or switch that character out....Don't Forget when finished head on upstairs to pick up the sun crest in a chest.

Yunalesca's quite easy to beat once you get the hang of it, actually. And if you saved beforehand when you had all your overdrives, you'll be fine, I'm sure. Here are some tips:

You should have Auron, Tidus and Yuna as your front line.

Form 1: Have Yuna cast Protect and Shell on Tidus, Auron, and herself. Tidus should cast Hastega (if you don't have it, Haste) on everyone too. Have Tidus Threaten her. Auron and Tidus should physically attack, and Yuna should keep casting Esuna whenever they're blinded.

Form 2: Have Yuna cast Reflect on Yunalesca (because she cures herself CONSTANTLY, and it can really be a nuisance). Also cast Shell on Yunalesca to halve the damage inflicted upon you because you will be zombified, so her curing technique will not help. (Do NOT use Lulu after this, or she will kill herself.) Keep attacking for this, and do NOT use any Aeon Overdrives at this point. Also, you should probably cure two out of three of your people with Holy Waters when they are zombified, especially the person who Yunalesca casts Regen on. If you cure all three, she will just use Zombie on you again.

Form 3: This is a very difficult form and you should've saved all your Aeon's Overdrives to this point. It's quite simple, actually - just summon all your Aeons, have them Overdrive as soon as you summon them, and if they don't die afterwards keep attacking with them. By the time you've used Bahamut's Overdrive, she will be long gone. It's also very likely she will die even before you use Bahamut. If this does not happen and your Aeons are cursed, simply use any other Overdrives that your characters have.

Hope this helps!

Theres really no point in buffing too much, as her regular attack dispels.

What I did:

I used Rikku Tidus and Auron in the start.

I made sure at least someone had something to counter Zombie. In this case I used Tidus, because I really cant afford Mega Death on Rikku/Auron. I started with one Hastega, and Star Curtain Rikku. I replaced Auron with Yuna, cast reflect on herself, Shell on Yunalesca. Next turn, I had wait, then I made Tidus attack, resulting in a blind, and an automatic Eye Drop. I had Rikku Steal, then use the Tablet on herself. Yuna just casted Holy. Tidus kept attacking, and next turn, switched out Rikku for Auron.

I had Auron toss a Mega Potion, and Yuna reflect Auron. Just kept attacking until second form. Everyone got zombied, and Yunalesca kept wasting her turns trying to cure me. Although curative magic reflected and healed her, it was shelled, and she simply could not keep up with Yuna's Dispel and Holy. That was pretty much it. Overdrives on final form.

These tips seem like all you need yo know, glad you beat the Keeper. If your still having trouble though just say and I'll jot down the official strategy guide (piggyback would love to find me =D)

What I meant is if someone posted a strategy for each boss then nobody would need to ask for help everytime they run into trouble. After I posted this I realized I shoulda just gone to gamefaqs.com to prevent bothering anyone. I found some tips and strategies but not for all the bosses and there are always those people who need help even on easy bosses cause they irritate me when I have to help them.

Your NOT bothering anybody asking Questions about the game man, ask what you like, thats what GT is for , nobody minds lending a helping hand, if they can, even if its something so simple..weve all had to learn at some stage :D.

As for G-Faqs, its HUGE compared to GT, it could fit GT in its back pocket well over 100 posts per day just on their FFX boards alone , As for the writers of the Long walkthroughs and Guides up there,with 99.9% of the things Xplained in the game, they are very good at what they do.

But they have, besides, having a Board section were peeps ask questions and chat, like on here, they also have a F&Q section seperate from the Forums, that is just for that purpose, What i mean is, if you were to write down every Boss strat on here not including fiends, for Tips, They have to go on the Main Page before they go into Tips, to post them all in one go in seperate individual threads would flood the Main Page, you could post so many in one thread, but depending on how long the Guides for each boss are, GT cuts off the posts after so many words..But short straight to the point Guides would work..

Plus, this is my take on this, Once a Tip has gone off the main page, people very rarely look into Them, i think people like to post Questions, Reason,besides having their name up in lights lol, and peeps love to help em out, well they can get more info, Different ways // strats to take down Bosses find items etc etc ,off different Gamers rather than just one individuals guide, Apologies for the Rant

Dont I know it lol, I have 7 Tips and I think they were only used when they were on the main page (judging by people asking the same questions lol). Check out the Tips tab at the top Sliver Overlord, and anything not there that you need to know, one of us will happily answer. (If I'm honest, it takes long enough to write a tip (which may not be read again as FREESHA explained) that writing a guide to every boss may take more time than I have lol).

Still, more than glad to help.

Oh but click "Read Tips" on the left hand side of the Tips button on the main page and not in a post and this will give you all the Tips on GT as the "Best Tips" section isn't working again =D

well i tried a variety of methods to defeat her, she is a tough opponent and i felt like giving up after several instances of defeat.. the one time i won i didnt use reflect, i couldnt remember not to use curaga or pray or any items to heal my characters otherwise i would've killed them off, she also uses regen and that will kill your characters off little by little until they're finally dead and besides, by the third and hardest round holy waters arent really useful, you may end up curing all your characters, if your lucky, right before a hellbiter but if your not lucky, right before a mega death.. so pay attention to health, open the third round with an aeon and a powerful overdrive, bahamut although i dont care for his overdrive breaks the damage limit which is very useful