The overall...challenge.

Well if this is a quest there is going to have to be a challenge.
Mostly I'm talking about the battles against Chip before everyone dies. The battles in hell
And the FINAL BOSS against Chip.

...Some are going have to be hard.

Final Boss fights for each odyssey should be pretty tough. Not easy enough to where you can beat them at level 20, but not hard enough to where you have to be level 40+

Hell and the final battles against Chip...put his AI on the higher levels. Final battle against Chip, MAXIMUM POWA!

The difficulty in my DO's are variable. I've went over the first three battles, but I'll go ahead and mention a few other notes here as well. It is important to note that I don't know the details about the Quest Maker. I'm also going to assume that you can, in fact, change the enemies costumes, though I'm going off of the screenshot a while back of AC Tifa vs AC Cloud...

Fourth: I don't know yet.
Fifth: Difficult.

~~DO 2~~

Notes:
-In the first DO, Jeryl has been at an equipment disadvantage. Throughout EVERY fight. In this one, that has been rectified.
-On the flip side, the decay is taking hold, and my level is decreasing in each fight. To compensate, my first battle I will be high leveled, and I keep going down in level, while my enemies increase in level. (I'm probably going to be going off of the assumption that you can...) If not possible, then my health keeps getting cut the longer things go on.
-This Destiny Odyssey, with the exception of one battle, is more difficult than the last.

Sixth battle is going to be fairly difficult. A bit harder than the typical battle of the last DO.
Seventh Battle....not so much.
Eighth Battle: Difficulty spike.
Ninth Battle: Somewhat easier than the eighth. Not by much, but easier.
Tenth: More than likely, harder than any other battle in my story. ANY other battle.

Unsure of my SI at this point.
Chip: Depending on your playstyle, either heaven or hell.

Yeah, I want to make Hero's DO a steady progression in challenge.

In the first battle, despite having his HP cut, he would be otherwise much stronger than Dragmire is, and thus is one of the easier fights in the story. The second and third battles are more or less average, while the fourth is a less extreme example of battle 1. Battle 5 would be the toughest fight yet. Battle 6 may actually be a step down in challenge, with 7 being equal or higher than 5. 8 would be a bit forgiving simply because of the sudden change in character, 9 gives Kitmeng & Dragmire an edge over Hero & Jeryl, and 10 is the hardest fight with a distinct advantage given to Dragmire.

... and I DO hope that you can change enemy costumes in Quest Mode. So far, it seems that Quick Battle doesn't let you do it, unless it's unlockable or something is being overlooked, but Quest Mode, IIRC, allows you to set everything for both sides, so it SHOULD let us do it... otherwise, we'd have a problem on our hands.