The following fiends can be unlocked through various means by capturing other fiends for the Monster Arena.
Earth Eater
Unlock two Area Conquest fiends.
Greater Sphere
Unlock two Species Conquest fiends.
Catastrophe
Unlock six Area Conquest fiends.
Th’uban
Unlock six Species Conquest fiends.
Neslug
Capture one of each fiend from every area in Spira.
Ultima Buster
Capture five of each fiend from every area in Spira.
Shinryu
Capture two of each underwater fiend in the Mt. Gagazet caves.
Nemesis
Capture ten of every fiend across Spira and defeat all of the other creations in the Monster Arena (including Original, Area and Species).
