A new trailer for Pokémon Ultra Sun & Ultra Moon has been released, showing off some minor details. The characters you play as have been redesigned, and there appears to be a new building in the empty plot in Hau'oli City. The video shows the new Lycanroc Dusk Form but provides no new details as yet.
There will also be a new key item in-game, the Z-Power Ring, which can activate to use an even wider variety of Z-Moves. UPDATE:Kommo-o has a new Z-Move Clangorous Soulblaze. Video below.
The story in Pokémon Ultra Sun & Ultra Moon will revolve around Necrozma. According to the press release, Ominous dark clouds begin to spread and the secrets of Necrozma and the Alola region, which were never disclosed in the previous games, will finally come to light.
Here's the trailer: