Alola Forms for various old Pokemon:
Exeggutor is Grass/Dragon
Vulpix is Ice type, evolves into Ninetales which is Ice/Fairy
Sandshrew is Ice/Steel, Sandslash has the same typing
New Pokemon:
Mudsdale's pre-evo is called Mudbray, Ground type.
Yungoos evolves into Gumshoos, Normal type.
Oricorio, which has 4 forms. These forms are Fire/Flying, Psychic/Flying, Electric/Flying and Ghost/Flying. New ability copies Dance moves.
Minior which is Rock/Flying, ability makes its shield break apart after being attacked.
Formantis, which evolves into Lurantis, both Grass type. They have the new move Solar Blade.
Mudsdale and Charizard can also be ridden along with other Pokemon using the PokeRide system.
A challenge for each island, where you have to meet specific conditions to complete it. At the end a "totem" Pokemon battle will occur. After completing the challenge you can fight the Kahuna of that island.
With Gyms rumored to not be in this game, this might be the replacement.
Video also expands on what the Z-Crystals do. Pokemon that hold the same type of Crystal as is set into the bracelet can perform stronger moves, as long as they are of the same type.