So, I thought 4 or 5 selectable difficulties would be a good idea. What I had in mind:
Beginner: The easiest difficulty. You recieve double bonus stats from defeating bosses, double EXP and all the enemy stats are halved. Bosses have their attacks downgraded.
Normal: The Normal Difficulty.
Hard: Enemies have slightly higher stats, 75% of your bonus stats, 75% EXP and enemies have their attacks upgraded.
Difficult: Enemies have even higher stats, 50% of your bonus stats, 50% EXP and bosses now have much more intelligent movelist AI.
Lunatic(only avaliable after beating the game once): Enemies have very high stats. You cannot level up. Skills take longer to level. Bonus stats however remain at 100%. Bosses will now do evil things like reducing your resistance to an element, then hitting you with the ultimate attack of said element.
Bonus stats are a special mechanic you get when you kill a boss. You get HP/SP/ATK/DEF/INT etc stats. It's the only way to increase your stats in Lunatic minus the consumable items, which are hard to come by unless you do 100% completion. Opinions?