The following information has not been confirmed yet so please read at your own risk and take it with a grain of salt!
A user on the popular Pokemon website, Smogon, disclosed that he had come across some top secret information about Pokemon Sun and Pokemon Moon. The information was apparently leaked by the team in charge of localizing the games in Chinese.
* Rowlet, Litten, and Popplio evolve into an archer, a wrestler, and a siren respectively—this matches this interesting “concept art” that has been circulating for awhile now but has yet to be confirmed or discredited.
* In addition to Salandit, there’s New Pokemon based on a mushroom, a dolphin, a sea cucumber, a snowman, and some sort of “rugby monkey”—a monkey with a ball, apparently?
* Rockruff will evolve into a werewolf. The official site mentions Rockruff howling at night prior to evolution in its flavor text and if this list was originally seen before then, not sure though when it first appeared, that’s a plus for it.
* Marshadow, a name we saw trademarked alongside the Box Legendaries a few months ago, apparently has a “very unique Typing”.
* There are apparently these special areas on the map that are hidden at first known as “districts” (?) where powerful Pokemon known as Overlords reside. Are these Legendaries? Or are they simply unusually powerful normal Pokemon with Hidden Abilities perhaps?
* No Gym Leaders. We’ve yet to see any real sign of Gyms this time around, and I was wondering about that honestly. Instead it seems the plot of the game involves forming a League and each Island is protected by an Island Leader. I assume the first one is Hala and Tapu Koko, who we’ve seen in previews, who serve as the Island Leaders of Melemele Island. It seems an actual Elite Four will eventually appear, perhaps in the post-game.
* The diamonds seen in the logo, and in the bracelets the playable characters wear, are collectible and seem to unlock functions somewhat simillar to Mega Evolution but not quite—perhaps this is related to the “Super Move” Pikachu is shown using in a shot posted to the official site. One of these stones apparently will be used to access Ash-Greninja.
* You can ride almost any Pokemon, though what “almost any” includes isn’t quite clear. A recent shot posted to the official site shows the player riding a Stoutland, so if this list was posted before that it’s another plus in its authenticity.
Below is a picture of the rumored final evolutions of Litten, Rowlet, and Popplio: