In the world of Pokémon, there are trainers, and then there are legends. Alex had always dreamed of being the latter. With a Pokémon X game that had been modified with a few fan-made tweaks (unofficially loaded via a CIA file on his 3DS), Alex had access to Pokémon not typically found in the Kalos region.
The search term "better" implies that this specific file provides an improved experience. Here is why users hunt for version 15 over version 0 (stock) or version 1.4. pokemon x update 15 cia better
The CIA Connection
Updating Pokémon X to Version 1.5 via CIA is highly recommended, as it fixes critical game-breaking bugs from the base version (1.0). In particular, the update resolves a notorious glitch that could corrupt your save file if you saved in the outer ring of Lumiose City. Why the 1.5 Update is Better Short Story: The Pokémon Adventure In the world