IGN.com and Jeux Video have revealed the evolution of Amaura, named Aurorus, and the evolution of Tyrunt, named Tyrantrum. Aurorus can learn a new Ice-type move called Freeze Dry (*cough*), which can freeze the opponent and is also super effective against Water-type Pokemon.
According to Nintendo World, after capturing a Pokemon, the Pokemon you used to battle it will now receive experience points!
An interview between Gamefreak and gaming website Polygon has revealed that Pokemon introduced in X and Y will not have Mega Evolutions. (If Mega Evolutions are some sort of artificial thing introduced by Team Flare that they have to work on over time, maybe that’s why? /my random fan theory)
Update (11:30 AM): With thanks to KurowaSan for the translation, an interview with Eurogamer has revealed that there will be a greater variety of wild Pokemon in the grass. The idea is that each time you enter tall grass, they want you to find a different Pokemon. Also, depending on the color of the flowers in the tall grass, the ratio of the Pokemon encounters and their types are different. Masuda also stated that there might be an easier way to obtain Shiny Pokemon, while Yoshida said that they wanted to make a Shiny Pokemon’s color stand out more.