As many of you are aware I believe someone else with information has been hinting and leaking some spoilers for the upcoming games Pokémon Omega Ruby and Pokémon Alpha Sapphire across other websites and forums. Let me start off by saying this person does have ties with the localization team at Nintendo that works closely with GameFreak to insure a worldwide release is possible. I won't comment on the reasons for Europe getting the game a week later than Japan and the Americas as I have no say in that decision. What you've heard so far is true. The Special Demos for the two games are to release this upcoming Wednesday worldwide. A Mega Lunatone and Mega Solrock will be available to obtain and transfer to your full games when they are released in your region.
To clarify, I myself work under the localization team for Nintendo and Omega Ruby and Alpha Sapphire have been our biggest project since X and Y due to the timeframe. I can confirm the Battle Frontier does make a return with some updates. It's larger and contains a lot more wild Pokémon than before. GameFreak included easy hotspots for training your Pokémon in specific stats for those of you who are more competitive. The Battle Frontier will have multiple terrains; two caves, grass lands, ocean, and a smaller desert to finds hordes of rare Pokémon and easily train your Pokémon. The Battle Frontier is also spread out a lot more and not just one big area. It contains multiple towns, cities, and routes. Think of it as a smaller additional region to explore. There are now eight Frontier facilities and a final facility where you'll be able to face off against previous Champions and Gym Leaders from past generations. That is correct, the World Tournament returns but is only unlockable after you've gotten all eight badges, beaten the Champion at least once, and obtain all eight Frontier Symbols.