You can buy Powersaves from Amazon, Play or any other gaming store/site.
No. Powersaves is an Action Replay device that allows you to edit your game. Powersaves allows you to get Mega Stones, Evolution Stones, Max money, Pokemiles, Battle Points, AZ's Floette, Diancie, Rare Candys etc
This is it: http://www.amazon.com/Action-Replay-Powersaves-Cheat-Device-Nintendo/dp/B00CQ9L1Z6