dark aeons are really only included in the international version. after completing the yunalesca fight u get the airship for free movement. and thats the time when they appear.
valefor: outside besaid temple
shiva: enter the guado mansion through the back door, go through that icy part of macalania, where u fought that al-bhed machina which sealed magic and aeons.
ifrit: outside the destroyed al-bhed home, speak to the girl standing next to the last hole, befor home.
ixion: thunder plains, a man standing under such an lightning protector.
bahamut: room where u fought yunalesca
magus sisters: mi'hen road.
joyinbo: cave of the stolen fayth, teleport into the last room then run to the save sphere.
anima:redo the thing on mount gagazet where u throwed a ball to that other ball(;-) can't tell it) with wakka.
with normal characters u can only use joyinbo , with zanmatou.
i killed most of them but i have my endfight party consisting of yuna tidus auron who all have min 25.000 hp all 255 strengh, defense and hit-chance. also all three should do (hit-expander) 99.999 dmg. then use (schutzengel) dont know how its called in american version.
three last advises: all three should have ribbon ability on their armor, use squalls blitzball ace(last overdrive- u get it when u do 50 energy rains) every hit on 99.999 should make it much more easy :-)
and...:u should go mi'hen road, then zanmatou that magus trio til u get perfect things for your three chosen party members, i advise three ribbons and then fetching ultimate weapons for hit-expander.
hope i helped
