For us FFX International newbies I thought a list of dark aeons would be good:
i) Dark Valefor (DAV)
LOCATION: Entrance to Besaid Village NOT beach. An event will occur where the
Summoner calls Yuna an infidel and sends Dark Valefor charging at you.
ii) Dark Ifrit (DAI)
LOCATION: Bikanel Island. The area before the entrance of Home, where you
started the Cactuar mini-game for Rikku’s Sigil. Talk to the Al Bhed
woman who claims she has lost her child in the ruins of Home, select Yes, then
watch the events that follow. When you walk to the cliff, the Al Bhed woman
will show herself as a Dark Summoner.
iii) Dark Ixion (DAIX)
LOCATION: Thunder Plains. Exit the Agency (where the airship drops you off)
and head north. Continue north and you notice a Bevelle solider resting under
a Lightning tower. Talk to him and he calls you a heathen and watch the events
that follow. You are required to fight Dark Ixion twice.
iv) Dark Shiva (DAS)
LOCATION: Head back to Macalania Temple. Walk to the entrance and the old
Guado will summon Dark Shiva who snaps at you.
v) Dark Bahamut (DAB)
LOCATION: Zanarkand Ruins, at the area where you fought Yunalesca. Dark
Bahamut will self-station himself there.
vi) Dark Yojimbo (DAYO)
LOCATION: Cavern of the Stolen Fayth, go to the back of the cavern using
either the teleport pad or walking there, then head back to the direction of
the Save Sphere and watch the events that follow. You are required to fight
Dark Yojimbo FIVE times.
vii) Dark Anima (DAA)
LOCATION: Mt.Gagazet. From the point where the airship drops you off, take the
teleport pad to ‘Cave Entrance’. This was the cave where you had
to solve a simple puzzle to form paths leading to the summit. Anyways, head
north downwards (do not take the stairs leading up) and then swim towards
north. Remember the ball-throwing puzzle? Do it again and when you hit the
center, Dark Anima will be pulled out of the ground. Save before fighting.
viii) Dark Magus Sisters (DAMS)
LOCATION FOR ALL 3: Mushroom Rock Road, enter via exit of Mi’ihen
Highroad. Walk in between the 2 summoners who are talking to each other, a
scene will occur. Run to the left at the nearest fork. Take the elevator up
and a cat and mouse chase game will occur. Your objective is to run until
Cindy (the fat one tires out). But if you are good enough, you can make it to
the end of the valley, take the elevator up, after the short scene, BEAT THEM
UP ONE BY ONE! Dark Cindy will be at the same place where she tired out.