(Generation 6) were released worldwide in October 2013. On December 12, 2013 , Nintendo pushed a critical software update, bringing the game to Version 1.5 (sometimes referred to as v1.5 or Revision 5). Unlike modern “quality-of-life” patches, this update was mandatory for online play and fixed a game-breaking save corruption bug.
: The update data for Pokémon X is specific to your game's region. Ensure the update matches your base game (e.g., use a USA update for a USA ROM). How to Install How to Update Pokémon X and Pokémon Y | Nintendo Support 22 Apr 2015 — pokemon x update 15 decrypted 3ds eur usa upd