The demo is coming to America
Mega Lunatone and Solrock with feature in the demo, and you receive one Megastone depending on the demo you get
Mega Flygon and Jirachi are programmed in
There are lots more megas that the leaker can not confirm just yet as they don't know 100%
New Trick House is amazing
Mega Milotic is a high-chance, with Water/Fairy and increased SpDef
Shiftry, Ludicolo, Butterfree, Zangoose, Seviper, some more gen 5, Raticate, Torkoal, Slaking, Exploud, Tropius, Azumarill, Ninetales and Mightyena were all talked about as possible Megas sometime during development and may be in
Luxray, Arcanine, Farfetch'd, Dragonite, Eelekross, Luvdisc, Linoone, Cincinno, Steelix, Raichu, Politoed, Gliscor, Weavile, Rotom, Bisharp and Walrein Megas have not been really discussed that the leaker has heard of
Items (including Lunatone/Solrock megastone) will transfer to ORAS from Demo
Johto starters back, but some people say they have megas and some don't
Character customization back in Pokecentres. Pokecentre in CoroCoro was the Elite Four one possibly.
Skintone back
More diverse encounters, so more like XY variety
Battle Frontier possibly back
Groudon/Kyogre still version exclusive atm
Contests revamped and very "beautiful"
Contests staying a secret, apparently will be very surprising and amazing
Canada will get demos
Pentagon currently stands for all Gen 6 Pokemon now, not just Kalos born
MOVE TUTORS BACK
A lot more post-game
Gym Leaders will get roster changes from their RSE counterparts
No new double megas like Mewtwo/Charizard at this stage
I will edit this as the leaker talks more, apparently they are going to try get more info on Monday but feel free to ask questions in the original post
DAY TWO
Safari Zone Updated
Hoopa available, but unsure on Volcanion
Has not heard of a Mega: Reuniclus, Staraptor, Torterra