Tower of Mastery and Shalour City | Walkthrough Pokemon X/Y Guide

Get into the city and head North for the tower of mastery. After completing battles there, You can go to the Shalour City gym, eastern part of the city. In the gym, go counter-clockwise till You reach a small tunnel on the far left of the room (of course, You have to battle the trainers You meet). Hop on in Your roller blades and reach Korrina. The battle will be pretty easy with a strong Psychic or Flying type. You must have either one of those by now. If not, head back to the cave before Shalour and get friendly with Mr. Mime/ Solosis or a Wobbuffet. After some training, one of them shall do the trick. Once You defeat Korrina, head out. Return to the tower for a Mega Ring and a battle. Now You have an ability to mega-evolve (check the faq). Head east for Road 12.