Posted this earlier in the starters thread, but it's relevant here.
All of the leaks have elements of info that they guessed right but some that still haven't been proven/are off. It's also possible some of it was guessed, piggy backed off of others, etc. I have to say that I think form changes nobody saw coming, even when a leak mentioned it, the majority dismissed it as false (myself included). I wanted it, but didn't believe it. I will see if I an try and break them down:
[Spoil]The Chinese leak was said to have appeared a week or less before salandit was revealed on July 7th. The Chinese leak said this originally:
* 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? If legit I imagine one or two of these Pokemon will be officially revealed soon, perhaps in CoroCoro, and if so that will speak to the legitimacy of this leak.
* 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". I've been speculating that Marshadow could be similar to Victini as a Mythical Pokemon revealed prior to the release of Sun and Moon, and I wonder if the upcoming Volcanion film could reveal him if my theory is correct at the end like what happened with Victini at the end of the final Diamond and Pearl film.
* 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.
Now some of this came true, some didn't pan out. We don't know how many Pokémon are rideable, but we know it's a rental service and not ours so I think this limilimitw many we will actually get. It does hint at the totem Pokémon with the overlord Pokémon comment. We also have no confirmation that part of the plot is forming the league... The Alola's culture seems to be celebrated and though I don't doubt a league will form, it isn't confirmed to be our mission in the plot. They don't seem to be "trying" to be Kantor, or some other region, but rather you're encouraged to travel Alola and expeeoence it like the locals
Another leak that surfaced was the Newest leak,It he bewear leak, also I believe called the Reddit leak? This one was released before Bewear and Mimmikyu's English names had been revealed,in which an anonymous poster gave the hint of bewear's name, as well as confirming Mimmikyu's english name before release (I know butchered the spelling on that, forgive me). It was also, to my knowledge, one of the first popular leaks to discuss Alola forms. This dates this leak at around July 15th I believe. This is what it said:
There actually are No Gyms
There is more than one evolution for Rockruff including a Werewolf
Yungoos' evolution is fat and hairy
Time works differently in each version
There are new forms of old Pokemon which are not Mega Evolutions but more along the line of Shellos/Wordam. Another chunk of information suggests that these are a few Pokemon that'll get new forms... Butterfree (Bug/Psychic), Rattata line (Dark), Nidoqueen/Nidoking (Poison/Fighting), Ninetails (Fire/Fairy), Growlithe line (Water), Abra line (Fighting), Duduo line (Fighting/Flying)
Pokemon transferred from the VC releases will have pre-gen 6 typings/stats
The stone bracelets have nothing to do with Synchro Evolution
Ash-Greninja is in the game
S.S Anne appears in the game
Larger, but not by much, amount of brand new Pokemon than last gen
Looker, Cynthia, Blue, Zinnia, AZ, and Lance all make appearances
Furfrou's hair cut can be changes in the new Amie
Some of the new forms for old Pokemon get new animations (Mentions the Abra line)
Transferring through Bank will be the only way to get some forms of old Pokemon
There is a flying type bird whose appearance varies each island
There is a 2 stage cat Pokemon that is Normal when captures but will inherit the fathers primary type as its 2nd type when hatched and the color/pattern varies by type
There is a Snowman like mentioned in the Chinese rumor and it is an Ice/Ghost 2 stager and it is an Ice/Ghost 2 stage
Now, we can't confirm most of this yet, but it did successfully predict forms and the bewear and mimmikyu names. However, it mis-labeled Ninetails fire/fairy when it's ice/fairy. If you just looked at Ninetails pic without the info, I can kind of see how you might think it fire fairy, as it is really whispy and it's colouring is similar to its shiny form. So I can see how it would be considered fire still...it doesn't have ice dripping from it or anything. And then there is fat hairy yungoos evolution... This is honestly subjective. He doesn't seem fat and hairy to me in evolution, so it sounds a bit off, but it could be argued. It's so much personal opinion. It does successfully mention the bird Pokémon with four forms, which is pretty big. This one could also just be piggy backing off of another leak that released before it... Or it has true info, or lucky guesses. Either way, we can't know for sure how much is true until more is revealed.
Then there is the new/old leak. This is from July 4th, also on Reddit. No one seemed to be talking about it until now, (the Bewear leak being more popular and well known), but it is older than the Bewear leak and could be around the same time, or just before/after the Chinese leak. This is what it says:
-Once it has learned Howl you can leave Rockruff at 1 of 4 cliffs overnight. It evolves differently on each island but only takes up 1 pokedex slot. The typings are Rock/Dark (Warewolf? Like in the Chinese Rumour), Rock/Fairy, Rock/Fighting, Rock/Steel
-Like Rockruff the starters have alternate evolutions that evolve based on the day/night but only take up 1 slot
-Some old Pokemon found in Alola are different to to those found in other regions mainly their markings/colours for example Alolan Pidove is pure white
-Arbok and a few others have unique markings based on the capture region (6 in total)
Some old Pokemon height/weight/stats change for example Alolan Rapidash has better Sp.Atrack than Attack and Alolan Dodrio are taller
-Unique breeding incenses have gone the way of the dodo. They now hatch like any other Pokemon
Pokemon transferred from older gens keep their stats/apperance they don't change into their Alolan forms.
-The Alolan forms are just new variants not new Pokemon
-Pokemon transferred from G6 will learn the same moves at the same levels and can only get G7 moves through TM/HMs
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-Pokemon transferred from G1 will have G5 typing/stats but G6 move pools
This is one of the older leaked info, but it does predict the new Alola forms, even if none specifically are mentioned, or if what has been mentioned hasn't been shown/revealed yet. The second leak I posted COULD be piggy backing off of this. Or they are both false, or both true, etc. Or maybe lucky guesses. We won't know for sure until time passes and more is shown to confirm/deny... but, it is interesting it predicted the Alola forms, because I don't think anyone really saw that coming, where as we were already predicting no gyms, etc. I don't think any of these leaks contradict each other either, but they newer ones, as said before, could be building off old ones. And yet, they all have something the predicted true before it being revealed unique to each leak (the starter evolutions, no gyms, the bewear name, the bird Pokémon Oricorio, Alola forms)[/spoil]