While there is no "Version 15" for Pokémon X , the final official update released for the game was Version 1.5. This update was critical for fixing a game-breaking bug in Lumiose City and ensuring stability for online play.
For users on a 3DS with custom firmware (like Luma3DS), the update is typically distributed as a CIA file. Pokemon X - hShop pokemon x update 15 3ds world cia region f portable
So you’re probably looking for a pre-patched or update CIA of Pokémon X version 1.5 to use on a modded 3DS or Citra emulator. While there is no "Version 15" for Pokémon
Below is a technical summary (draft "paper") regarding this specific software package and its application for Nintendo 3DS users using custom firmware (CFW). Technical Summary: Pokémon X Update 1.5 (3DS) Software ID: 0004000E00055D00 (Update Title ID). Pokemon X - hShop So you’re probably looking