#o-powers

I can now tell you categorically that the game calculates the Amulet Coin first, doubling the original amount, and then Prize Money multiplies that doubled amount afterwards.

For example, Earl Gruosi in the Battle Chateau normally yields exactly P5,000 upon defeat.

The Amulet Coin doubles this to P10,000.

Prize Money Level 3 then triples this to P30,000.

So, beating someone who would normally be worth P5,000 can actually net you a tidy P30,000 instead, which I'd say is definitely worth doing. From the moment I was able to get into the Battle Chateau, money ceased to be any kind of an issue for me for exactly this reason.

You need to use a level 1 O-Power fifteen times to get it to level 2, and then you need to use that level 2 O-Power thirty times to get it to level 3, which is the maximum.

The more steps you've taken over the course of the day, the faster your O-Power gauge will replenish itself. It does this over time, rather than as you take steps, so you can literally just stand there and let it do its thing, or even turn the game off and come back to it later if you've got nothing else to do in the meantime. Play with your team in Amie, that's worth doing, too.

You don't have to wait for the O-Power you've just used to expire before using it again. You can literally spam the things over and over again until your gauge runs out and they'll all count towards the number of times you've used it, so if you've got one you're trying to level up in a hurry, just spam the shit out of it even when you're not going to be using it. Your gauge is going to refill either way, so every time you've got enough to use the O-Power you're trying to level up - and they're literally all worth levelling and using - just use it. 

Higher level O-Powers are more expensive to use, but their effects are hugely multiplied over their lower level versions. For example, in the case of prize money:

Level 1 gives you 150% prize money. If you beat someone who would normally yield $1000, you would then get $1500 using Prize Money Level 1.

Level 2 gives you 200% prize money - doubling it. If you beat someone who would normally yield $1000, you would then get $2000 using Prize Money Level 2.

Level 3 gives you 300% prize money - tripling it. If you beat someone who would normally yield $1000, you would then get $3000 using Prize Money Level 3.

All of the O-Powers scale up in a similar way, making the Level 3 versions very powerful and very useful indeed.