I got some new info just some hours ago and I didn't know where to post it so someone could take it seriously...

So here we go, this is all I got:

- Sun/Moon time difference will be based on your 3DS clock
- Sun stone and Moon stone will only work depending on the time of the day
- Some new Pokemon will evolve using stones
- Gen 1 VC Pokemon's ability and nature will be generated randomnly when transferred to S/M.
- They will keep the same type as in gen 1 (Clefairy: Normal)
- There will be a third legendary representing the earth which is not Marshadow
- Zygarde has an important role in the main plot
- Type:Null will have a second type when bred with other types of Pokemon
- An egg of Chansey will always hatch into Happini. Incenses no longer required.
- Eevee will evolve into Sylveon without requiring Amie stats
- Shauna, Clemont and Bonnie will make a return
- Hordes make a return and you will be able to catch them without fainting the other 4
- Rockruff and the starters have 2 different final evolutions depending on the time of the day
- Ultra Beasts are anomalies coming from an alternate reality were people and Pokemon are the same thing, they will cause a lot of problems in Alola. Special "abilities" are required in order to beat them.

This information comes from a reliable source that has leaked some information in the past but didn't want to be exposed anymore. Please pick the info with a grain of salt because he couldn't speak about all details and some information may be changed or not accurate.