No, everything is right. Dark Valefor is there and there is no way around him, you have to beat him. It has 800000 HP. Though it is said that you can deal with Dark Aeons (there dark versions of ALL aeons) with normal means, that is by fighting with your characters and summoning your own aeons, if you do not wish or can't do it, there is a simple solution: find the Yojimbo hidden Aeon, make Yuna have the first turn in the battle, and summon him. Pay him a lot of money (like 40000 gil) and he should kill him in one hit. I recomend you read through this forum as at least third part of all posts is regarding the Dark Aeons. <img src="/images/graemlins/smile.gif" alt="" /> Good luck.