I believe you can buy the EV train Card for 10AP each after the events in terajuma with Crawli. Right after that, there is a boat in terajuma that leads you back to East Gearen and at this moment you'll be able to buy these cards at the AP Store. (I have not witnessed it by myself but that's what i read on another forum, but i am 100% sure you can have access to EV training after Angie battle)