There is a Cab in Pokemon X & Y That Wants to Eat Your Save Game and Make You Cry

Pokemon X/Y lets you save your game pretty much anywhere you want, but there is one location you might want to avoid. Several people have now posted complaints about their game freezing after saving near a specific location outside of Lumiose City. There are several Youtube videos where you can see the result of the glitch in action, but this post on GameFAQs explains the problem nicely.

“I saved near a cab in Lumiose City and now whenever I try to restart my game it immediately freeezes. It loads my trainer and all of my clothes as well as the buildings and their lighting effects, but none of the objects in the streets or the textures on the buildings show up.Pokémon-Amie is also frozen on my bottom-screen without loading anything and the game won’t return to the Home menu when I push my button. I can hard-shutoff, but the 3DS internal software is completely frozen.”
The good news is that the post makes clear that all of your clothes will load, so your trainer will not be wandering around naked in all their shame. The bad news is that there isn’t a real fix for this yet, so if it happens to you the only solution so far is to start up a new game. Several other individuals have complained about similar problems, while other say they’ve saved there multiple times and encountered no issues. Still, it might be for the best if you just wait until you get inside one of the buildings in Lumiose City before saving if you value your Pokemon.