Look for .3ds files for emulators or .cia files if you are installing directly onto a 3DS console.
While "Free ROM" sites are all over the internet, they often come with risks like malware or broken files. The safest and most ethical way to get your ROM is to . Homebrew your 3DS: Use a tool like Luma3DS. Pokemon Alpha Sapphire ROM Download Free For 3D...
Use this application on your console to "dump" your game into a .3ds or .cia file. Look for