How do I defeat Gigantuar?
Gigantuar has high Defenses and Evasion, both magical and physical, so you will need to attack it with defense-ignoring and unblockable attacks. See [52] for a list of these. Boost your HP before the battle with Red Caps and Muscle Belts, and try to cast Reraise as much as possible. Attacking it results in a Knockdown attack, a very powerful physical hit. It will also alternate between two and four 1000 Needles attacks, and it will do 10,000 Needles (10 x 1000 Needles) when it dies. If all of your characters have at least 2000 HP and Reraise, you will survive. If not, you can always Jump or summon Quetzalli just before the final attack. If you absolutely cannot defeat Gigantuar, note that it will only appear on a certain tile in the southwest part to the Maranda desert. By avoiding that tile, Gigantuar will not appear, and you can feel free to farm Cactuars for AP in peace.