I feel like nap time should work like this:
It takes a certain amount of time for 1 HP to regenerate,
so multiply that time by how many HP you need for full health.
Perhaps 5 seconds per HP,
such that a 400 HP Moga takes about half an hour to regenerate.
Stopping nap time before the Moga's fully healed
will keep any regenerated HP,
rather than forcing you to start over.
I certainly agree with in-game currency.
I'd love to trade Mogas.
I have extras thanks to those stupid quests
when I already captured the Moga
and it was like, "Oh hey, now go capture this one you already have!"
Maybe even count it toward the quest
if you receive the Moga from trading with a friend.
Battling people would be awesome! surprised
I wonder what the reward would be.
Experience, items, something you each wager...?
Maybe even battling in a tournament against AIs.
Have an arena where you can battle at various levels,
beat one trainer and move on to the next,
until you reach the highest
(kinda like the Blackjack game Gaia has).
Maybe offer experience along with special rewards
(like an Epic Moga for defeating a high level trainer).