Ultimate Weapon can only be defeated once it hovers in the "final location" near Cosmo Canyon. In order to force Ultimate to fly to this location, one must reduce its HP to ≤ 20,000. The monster begins with 100,000 HP, and (much like Doom Gaze in FFVI) loses HP during battles, which is not recovered for subsequent fights. Consequently, Ultimate Weapon can be forced to the final site almost immediately, or the process can be dragged out for however long one desires.

After the Mideel incident, the first optional battle with Ultimate will take place at a "lake" on the initial continent, where a forest used to be located. After this, it can eventually be chased to one of several locations; these sites are Midgar, the Northern Crater, Mideel, Ft. Condor, Gongaga, the Nibelheim area, and the entrance to the path to North Corel. The battle location will shuffle randomly between these locations until 80,000+ HP has been taken off, at which time Ultimate can be chased to the Cosmo Area.