The update data for Pokémon X is different from Pokémon Y ; you must ensure the update matches your specific game version and region (EUR or USA).
Official patch notes from sources like Serebii and Nintendo Support highlight the following: Pokemon Y: Update 1.5 [Decrypted] 3DS (EUR/USA)...
Reverted a temporary change, ensuring that Pokémon species names—rather than custom nicknames—were displayed during official online battles. The update data for Pokémon X is different
Fixed a specific issue that caused players to disconnect during Random Matchups and Online Competitions. is the final official software update released for
is the final official software update released for the Nintendo 3DS title. While the eShop has largely closed, game updates like this remain available to download for users who own the software. Update Overview Release Date: April 22, 2015.
The update primarily focused on "various bug fixes" to improve the overall gaming experience.