in the final part of the dungeon before you find yojimbo thats where you find tonberrys.if you encounter dark yojimbo(if you have the version with him on.)good luck! and also good luck finding the tonberrys.all i can say for ultima buster is have overdrives up,high hp and speed and strenght,auto haste shell and protect(i suppose you can just cast hastega.)and also sacrifice aeons when neccasary.