At the Pokémon Game Show this weekend in Japan, demos of X&Y were available for play. Several small bits of information have come out from that.
In the demo you battle your rival, then go to see Professor Sycamore who tells you about Mega Evolution and gives you a Mewtwo and you battle him. Its unclear if this is just a special battle for the demo or actual gameplay (it would be quite late in the game if so). There is a special Mega Evolution button on the fight screen; when pressed the Pokémon Mega-Evolves and can use a move on the same turn. Graphics have also been improved by having each move slot the same color as the type of move.
Pokemon X/Y move screen and Mega Evolution button
The Fairy type is confirmed to be not very effective against Fire types, and the Fire type is neutral against Fairy. In the overworld, running the default and the player must hold B to walk.
Update: an image appearing to show Sylveons shiny form has surfaced, continue for details.
: Tail Whip, Fairy Wind, Quick Attack, Swift.
: Psybeam, Fire Spin, Tail Whip, Flame Charge.
: Tail Whip, Thundershock, Quick Attack, Parabolic Charge.


Using the Fly HM keeps the generic dark bird animation.


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