I have found that there are other unlockables besides characters and stages (arenas).

Does anyone know how to unlock the Powered-Up versions of the different Mamodo? I have unlocked both the Powered-Up versions of Zatch/Kiyo & Kiddo/Dr. Riddles. Not, exactly, sure how I did it, though. I was just playing Story mode with certain characters and encountered them. When I defeated them, they became unlocked (after I completed the Story).

Also, how do you unlock the Powered-Up Mode of Time Attack? I read somewhere that this is how you have to unlock certain Powered-Up Mamodo.

Finally, I've read about there being a 7th spell for both Zatch/Kiyo & Zeno/Dufort. Can some someone give more info about this and are there unlockable spells for the other Mamodo?