Max out the rank for all Phoenix classes. Must go from 98 to 99 without using a Heart enhancement.
You must max ALL classes of Kluke's Phoenix Shadow to level 99, all 9 classes must be leveled up to 99.
6.Black Belt - A great find by Skadi And Omega a direct quote from his comment: "You can steal Black Belts from Corrosive Poo on disc 2, you can spawn him by going to Ancient Ruins - Caverns, North West of Talta Village. When you get there, you will see Jumbo Poo guarding a chest, you have to defeat him and open the chest to spawn Corrosive Poo. Back Attack Corrosive Poo, use Steal (don't use Loot, Steal was much more successful for me), if you get Ultra Medicine, reload your game (there is a save point right next to where CP spawns). If you get a Black Belt, flee from the fight, save, reload save, do it again as many times as you want. You only need 5 though. It should be noted that you need to have the Blue Device to access this area, which you get in Baroy Town."
Note: You can also equip a Dog Collar or use Garlic on your allies to attract some more far off enemies into your field.