Pokémon X and Pokémon Y

Because of 3DS they can patch the game later AFAIK. And they can release mystery legendaries and actually keep them a mystery until their event is ready.

Indeed, and i'm quite excited about something like that happening. Starting from this generation they can add pokemon after the games release, which would keep the game interesting if new pokemon kept being revealed even after the game is released.

Of course, previous event legendaries were "revealed", but we knew about them anyway.

People are hearing "DLC" and kicking up a shitstorm. but come on, we had DLC already in the form of Wifi events, the tournaments in Black and White 2 and tons of other stuff. The game being on the 3DS just opens up so many possibilities including expansions.