People are probably going to have a lot to say and discuss about this, so regardless of your views on the topic, please keep things civil with one another.
A new feature in XY is Mega Evolution. It involves certain Pokemon becoming more powerful versions of themselves and they change the way they look and sometimes their types and abilities. They don't seem to be actual evolutions and aren't referred to as formes either, so it seems possible that they are more like "super-charged" versions of the Pokemon.
Here's what we know so far:
-Mega Mawile is Steel/Fairy with Huge Power. It has increased Def and Sp.Def stats.
-Mega Ampharos is Electric/Dragon with Mold Breaker. Seems it can now learn Dragon attacks.
-Mega Absol is Dark with Magic Bounce. It has increased Atk and Speed.
-Mega Lucario is Fighting/Steel with Adaptability. It has increased Atk.
-Mega Blaziken is Fire/Fighting with Speed Boost. It has increased Atk.
-Mega Mewtwo is Psychic with Insomnia. It has increased Sp.Atk.
-Mega Kangaskhan has the new ability Parental Bond which allows it to attack twice. Any type and stat changes are currently unknown.
-They are only activated during battle and appear to be super-charged versions of the Pokemon.
-You can only have one per team.
-The Pokemon needs to be holding their specific Mega Stone as well as other, so far unspecified, requirements before it can transform.
-The new gym leader Korrina is said to know all about Mega Evolution.
-The Tower of Mastery in Shalour City is said to hold some secrets of Mega Evolution.
-Torchic is to be given over Wi-Fi from Oct 12th to Jan 2014 with its Mega Stone, Blazikenite, to be used to get MegaBlaziken.