How to Defeat Dark Aeons

Grind your party. Dark Aeons have extremely high stats. You might even get shocked the first time you face one as you miss every single shot and he or she just finishes your party with one flick. With this, you need to max at least all your most important stats (HP, MP, Strength, Defense, Agility, Accuracy). You may not need to upgrade your other skills (Magic, Evasion, etc.) because all Dark Aeons absorb elemental attacks, are still strong even against Ultima, and almost never miss physical attacks.

• It is recommended to choose your favorite three characters and focus on maxing them up. This will make the process easier and lessen the spheres you'll be needing
• You need EXP for traversing your Sphere grid. A good grinding place would be Omega Ruins, especially the shadowy areas where huge monsters also give huge experiences.
• You need +4, +300 HP, and +40 MP spheres. You can get all kinds of spheres at the Monster Arena where special types of monster drop a measly one (or two for overkills) sphere each fight. This takes a lot of patience and strategy since every monster is a boss battle all on its own.
• You need all the space on the Sphere grid. There's no room for blank spots on your grid if you want to max your stats. This sounds tedious, but you need to clear out all lesser nodes, including +1 to +3, +100 to +200 nodes). Strictly speaking, you can customize 775 out of 860 nodes (Standard Grid) or 707 out of 792 nodes (Expert Grid).

Get Celestial Everything. Obviously, you can't defeat any Dark Aeon without Break Damage Limit so you need to do the specific tasks to earn each of your party's Celestial Weapon and power them up with crests and sigils.

• It's not recommended to attain BDL by customization since Dark Matter is simply too rare. You might want to save them for Ribbon.
• Celestial Armors isn't really a thing but most gamers would agree they include the following: Auto-Haste, Auto-Protect, Break HP Limit, and Ribbon.
• You can get weapons with automatic BHL or Ribbon from Dark Aeons themselves. A preferred Dark Aeon to drop these is Yojimbo, whom you have to fight five times to finish off. Engage him four times and if you haven't got your desired armor yet, leave using the Save Sphere and chase him all over again.
• Since Ribbon does not protect your party from Death and Breaks, some gamers also prefer Auto-Phoenix to be part of the Armors' abilities. One possible flaw of this is that Phoenix only gives a quarter of a character's total HP, allowing your character to be instantaneously revived but weak, and able to induce damage less than the preferred 99,999.

Use quick hit. This is why maxing your MP levels is important. Dark Aeons have extremely high Agility (especially Dark Shiva and Dark Bahamut) which you must counter by cutting the opponent's turn as much as possible (Haste is simply not enough).

Use your Aeons as your shield. Most Dark Aeons' overdrives kill the entire party (especially Yojimbo) so whenever his or her overdrive fires up in the next turn, summon Yuna to sacrifice one of your Aeons for you. It's for a good cause.