Pokémon Omega Ruby to version 1.4, you must apply a specific update patch to your existing game. There is no official "Version 1.4 ROM" for download; rather, the update is a separate file that modifies the base game. Update Instructions
Always read the README.txt inside the patch download—it contains unique change logs and encounter tables for that specific V1.4 version.
: Highlight the Pokémon Omega Ruby icon. If your console is online, a message should appear prompting you to update.