Fairy will be a new type. It is weak to Poison and Steel, immune to Dragon, super effective against Dragon, Dark, and Fighting, and Fire and Psychic-type Pokemon take half damage from it.
Sylveon is Fairy-type. Some older Pokemon will be reclassified to Fairy, such as Mawile (Steel/Fairy).
Mewtwo has two new formes, not just one. Both are activated via items.
The professor's English name is Patrice.
The Starter final evolutions are Fire/Psychic, Grass/Fighting, and Water/Dark.
The first Gym is Bug, the second is Fairy, and the fourth is Fighting.
A few attacks will be dual-typed.
There will be a new type of battling style that Flying-type Pokemon and Pokemon with Levitate can participate in.
You will be able to see a Pokemon's EVs at a certain in-game facility. You will be able to boost the EVs through mini-games. It will take about two hours to get one stat to max EVs.