Ok, I have found out where to get them. Talk to the man in the suit in the Pokemon Centre on South Boulevard in Lumiose City. He will sell you stuff in exchange for Poke Miles. If you don't know what they are, then he will explain them to you. You can check your current Poke Miles on your trainer card. He sells a lot of healing stuff, along with Rare Candies and PP Ups (sorry, no maxes). However, PP UPs are the most expensive item there and cost 1,000 poke miles each. If you compare that to the Full Heal which is 30 and the Hyper Potion which is 60, you will see what I mean by expensive.