From Bulbanews, your community Pokémon newspaper.
Holding Mega Stone of opposite version
||This local article reports on an event in a specific geographical location. It may not be relevant for all readers.
At GAME stores in the UK, starting tomorrow (July 11, 2014) Charizard holding the Charizardite Y will be distributed to Pokémon X, while Charizard holding the Charizardite X will be distributed to Pokémon Y. This distribution will last until August 10, 2014. This distribution is to promote the launch of Nintendo Zones in GAME stores. This Charizard will be distributed via Nintendo Zone, or via serial code for stores without Nintendo Zones.
These Charizard will likely be the same as the ones distributed via serial code for Japanese region games and the ones distributed by serial code for Korean region games.