Mega Steelix and Mega Glalie will be in the ORAS demo:
Here are some more details about the demo:
Head to Hoenn Early with the Pokémon Trainer Club!
Look for a Special Demo Version code in the October Pokémon Trainer Club newsletter!
Want to play the Pokémon Omega Ruby and Pokémon Alpha Sapphire Special Demo Version? Look for a special code in the October edition of the Pokémon Trainer Club newsletter. Then, use the special code in Nintendo eShop to download the Special Demo Version directly to your Nintendo 3DS or Nintendo 2DS system!
The Special Demo Version features a unique adventure where you can encounter cool Pokémon, including ones that Mega Evolve! Plus, you'll be able to bring reward items you obtained in the demo into Pokémon Omega Ruby and Pokémon Alpha Sapphire.