Red XIII Ultimate Weapon
Red XIII’s weapon, Limited Moon, can be obtained from Bugenhagen in Cosmo Canyon – after the point at which Bugenhagen comes with you to the city of the ancients. This can also be obtained at the end of disc 2 and even disc 3.
To do maximum damage with Limited Moon, you must make sure that Red XIII’s MP gauge is full. So effectively, if you are to use Red XIII in your final party, it would be advisable to have him as a physical attacker, otherwise there isn’t much point in attacking with him if you will cast magic.