NEED IDEAS FOR ENEMY LEVELS IN RPG 2K3 OR PICK THE BEST IDEA

I've been dabbling in RPG Maker 2K3. I've got a lot of side quests. The downside is if you are very uber you just plod through enemies with zero challenge. So I've been wondering if anyone has any ideas for enemy levels. You get stronger and so do the enemies. There doesn't seem to be any good way. You can adjust enemy MP / HP but not Attack. Here are my ideas so far...

Battles >>
- Have hidden enemies that reveal themselves when you've reached a certain level. Like adding extra enemies to the fight.
- Have lesser enemies morph into bigger enemies based on the player level.
- Enemy HP and MP go up based on player level... this is a bad idea since their attack strength doesn't go up.
- Temporarily put the player back to the level they should be on the side mission, which opens up all sorts of problems.
- Temporarily make the player have a new party for side missions. That opens up a new can of worms too since RPGs are open. Unless you make it like GTA and lock the player into one quest.
- Just not have side quests with battles.
- Lock the player out of certain side quests based on their stats / level... denying the player from seeing a lot of content.