Nintendo announced the video games in February, but didn't release any information outside of a few shots of concept art and confirmation that the game is the first in a "new generation", i.e. not a remake or sequel game to Pokemon X and Pokemon Y.
It's widely speculated that we'll see the mascot legendary Pokemon for the game, as well as the new starter Pokemon, but it's possible Nintendo could also show off some of the game's new features.
Based on concept art, many fans believe that Pokemon Sun and Pokemon Moon will allow fans to drive for the first time. Concept art also hinted at hotels somehow being used in the new game.