Finding a direct "download" for a randomized Pokémon X or Y ROM is difficult because sharing pre-randomized ROM files is generally illegal and against many site policies. Instead, the standard and safest method is to download a randomizer tool and apply it to a copy of your own game file Recommended Randomizer Tools
file of Pokémon X or Y. This is usually "dumped" from your own physical cartridge using a hacked 3DS with Decrypt the File Pokemon X And Y Randomizer Rom Download
: If you plan to use an emulator like Citra, the ROM must be Finding a direct "download" for a randomized Pokémon
for a detailed technical guide on handling 3DS game formats. Read through the UPR-FVX GitHub Read through the UPR-FVX GitHub for advanced 3DS
for advanced 3DS editing from the community at Project Pokémon. Check out the Universal Pokémon Randomizer ZX Wiki