So with the localised names from the English trailer, and new information streaming in...
Tapu Koko, the Guardian Pokemon of Melemele Island, is Electric/Fairy and has a new Ability called Electric Surge, which automatically turns the field into Electric Terrain (the field effect from using the move Electric Terrain) when it enters battle. It also knows a new move named Nature's Madness, which halves the opponent's Pokemon HP.
Charjabug is Bug/Electric, and the evolved form of Grubbin. It has the new Ability called Battery, which boosts the Special Attack of its partners in Doubles/Triples. It knows Spark.
Vikavolt is Bug/Electric, and the evolved form of Charjabug. It has the Ability Levitate. It knows Zap Cannon. Grubbin is the regional Bug Pokemon with a cocoon stage.
Drampa is Normal/Dragon. It can have a new Ability called Berserk, or Sap Sipper. Berserk increases Special Attack when activated, when its HP drops below 50%. It knows Dragon Breath.
Bruxish is Water/Psychic. It can have a new Ability called Dazzling, or Strong Jaw. Dazzling prevents moves with an increased Speed Priority from hitting, as shown in the video when Pikachu tried to use Quick Attack on it, but failed. It knows Psywave.
Cutiefly is Bug/Fairy. It knows Fairy Wind. It can have the Abilities Honey Gather, or Shield Dust.
Togedemaru is Electric/Steel-type, and can have the Abilities Iron Barbs, or Lightning Rod. It knows Discharge and Spark, and is the regional Pika-clone.
Iwanko is called Rockruff.
Nekkoala is called Komala, and it's new Ability is now called Comatose.
Riding Pokemon is back!
Also, Zygarde's Ability is now called Power Construct, which activates when HP drops below 50%. Again, does this mean that its previous Aura Break Ability is exclusive to XYORAS now? Who knows?