III: Fought Odin, Bahamut, and Leviathan to obtain them.

IV: Same as III.

V: Same as before; Carbuncle, Catoblepas, Ifrit, Ramuh, Shiva, added. (To fight them to obtain them anyway.)

VI: Ifrit, Shiva. Sort of. Most were Magicite.

VII: Don't recall any..

VIII: Brothers, Bahamut, Diablos, Giant Cactuar, Tonberry King, Diablos, and Cerberus, as listed in an above post.

IX: You fight Ark. Don't get it until you get two Pumice Pieces and synth them though...

X: Fought Anima. Technically, you fight all your Aeons in the game, at the end of the game, Dona, Isaaru, Belgemine, and if you have PAL or International, you fight the Dark Aeons.