In games where everyone can be everything (FF5, FF7, FF8, Original FF12), I like to categorize characters into roles. I intentionally limit what each character can or cannot learn. If it's a game with 4 characters (like FF5), I'd have 1 heavy melee/tank, 1 fast melee, 1 offensive mage and 1 defensive mage. If it's 3 (FF7, FF8), I'd have a Paladin type (tanky/heavy melee but with healing), a mage type (with back up healing) and utility (mostly attacks but with buff/debuff).