This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
There are a number of different strategies to use. Here's one:
Have one or two characters master the Ninja and Hunter jobs. Then,
remove their class (change them to "bare"), and set them to use the
2-handed ability and the four-attack command.
With two weapons (preferably weapons from Kuza Castle or better) and the
four-attack command, the character will hit the boss eight times for big
damage each time. With the more powerful weapons, it's not uncommon to
be doing 10,000 points of damage per attack...