Involved with the game briefly, yadda yadda drunk and AMA.

Getting this out of the way:

Synchro crap is not in the game.

Litten's final evo is not partially Ground, it's Dark.

Popplio's final evo is not partially Fighting, it's Fairy.

92 new mons.

There's a crab mon that's my new favorite.

Not including those 92, 18 new Megas ALL for past-gen pokes.

2 new forms for past-gen pokes.

No new standard evolutions for past-gen pokes.

No vehicle travel outside of cutscenes.

No new types.

Pokemon brought into Pokebank from the virtual console games are allocated IVs/gender/etc at complete random. Standard gender ratios and DVs from RBYG are ignored.

Dewgong gets a Mega.
Arbok gets a Mega.
Crustle gets a Mega.
Farfetch'd gets nothing new.

Only four legendaries this time.

No additional difficulty modes - game is around XY difficulty but feels even more spoonfed with Rotomdex acting as Navi all the time.

Major change is rework of IVs and shiny mechanics.

IVs may now be increased or decreased with a hard-to-get item post-game. Think lots of battle points.

Shininess retains ORAS odds, but pokes are no longer locked to the standard "shiny" palette for each poke. Palette colors are now randomly determined when a shiny is found/hatched.

In this way, breeding is now less of an IV game and more about shiny hunting for cool looking palettes.

Main game themes are flowers/colors/friendship.

Mostly just answering yes/no shit from here on out. Have fun.