I've beat the game, so I decided to do some pointless stuff, like changing my wardrobe. However, i'm low on money after buying from Boutique Couture. Where can I get more?
Restaurants in Lumiose City: Yeah, they present lots of money. Only, you have to have some beforehand in order to enter.
Amulet Coin: Equip to Pokemon and battle. During battles of the Lumiose restaurants = lots of moolah!
O-powers: to get this one that increases Poke income, go to the Mr. Bondings of Cyllage City hotel. Combine this with Amulet Coin!
the fastes way I can think of is getting the mushrooms from the restaurants and selling them
here is a link on how to do it and how much you get: http://www.youtube.com/watch?v=e0S6B1pah64
Look here Game Zone and Here Neoseeker for ALL the details on how to get quick money.
Hope I helped!