I wanna use the coins on puzzles though. I've tried to use at least 100+ of them on Quest already with no White. And if I must choose...

Not sure integrating them both is a good idea, many people live where there are few 3DS owners and hence few completed puzzles. It's already annoying enough to beat Find Mii and its sequel if you don't live in Japan, don't still go to university or hate conventions and events.

I like the health bar idea and the king being playable. i think though find mii 3 should be for the wii u as a game you buy from the store. You wouldn't need playcoins to buy heroes because you could get them through quests and helping the residents of the kingdom. You could have both quests from find mii 2 and they should make a bigger map with you being ale to explore more of the levels and the maps themselves.

The issue with making it a Wii U game is that you'd need to do a hell of a lot of redesigning to make it work without StreetPass or Play Coins. Would you get new Miis through Miiverse? That'd make the game ludicrously easy. And if you got them in game, it'd mean the game could basically be beaten in about three hours flat because you wouldn't have to acquire Miis and Wanderers via various external means.

Really all I want in Find Mii 3 is a hat that is Pit's golden laurel crown. That would be my favorite hat hands down.

True but they could make it where you needed in game money to buy miis at the miiverse to fight or the wandering heroes. The coins could be obtained by helping people without fighting enemies to get money to buy troops but it would be hard to balance like you said.