Nintendo has released a demo for "Pokemon Sun & Moon" ahead of its official release next month, and you can get an Ash-Greninja for the main game by finishing it. That's not the only good thing you can find from the demo though, playing it again can reveal some secrets you definitely missed the first time.
Polygon reports that some enterprising "Pokemon Sun & Moon" players on Reddit ran the game again and found some new things. They're basically different item rewards you can get by talking to people in the game certain days after you start playing the demo, as there seems to be an internal calendar it's following.
For example, you can get 10 Pretty Wings if you go to the Pokemon Center the very next day you start playing the "Pokemon Sun & Moon" demo. Another reward is a Balm Mushroom given by the man with the Pikachu in the city hall if you go talk to him after 12 days. Another one is a Comet Shard from the sad-looking woman in the ferry terminal. The store manager also promises "goodies" after a month, referencing the main game's official release.
The items you get in the demo will definitely carry over to your inventory when "Pokemon Sun & Moon" finally drops next month. Other than those rewards, the different "secrets" you can dig up in the demo is just different dialogue from the NPCs. It's a nice little touch if you want to keep playing, but beyond that, there's not much more to offer.
Meanwhile, determined tech-savvy players have managed to hack into the data files of the game, revealing the rest of the Alola Pokedex. Because of this, the final evolutions of the starters have been revealed before Nintendo officially announced them. "Pokemon Sun & Moon" releases for the Nintendo 3DS on November 18.