According to the official website, you can transfer your Pokémon from XYORAS to Sun & Moon through Pokémon Bank, but even more, you can transfer Pokémon you caught in the Virtual Console versions of Red, Blue and Yellow (which you can apparently buy five times each, once for every language the Pokémon games are translated to in Europe). I wonder if you'll be able to get your RBY's Missingno onto Pokémon Sun & Moon. Also interesting to see that China is now getting the games in Chinese as well.

I really hope that 'Sun' and 'Moon' are an indication that these games are going to reincorporate the visible day/night mechanic. It was strange going from Black and White to X and Y and not having the night fall in-game anymore.