First up we have Togederamu, this pokemon is an electric type and is more than likely the Pikachu clone for this generation. In its video it uses an electric type attack that could be volt tackle or wild charge. Unsure what type of rodent its based on but it produces spines from its body during its idle animation.
Next up is Bruxish which is a new fish like Pokemon, it has a new ability called Dazzle or Dazzling which stops the use of priority moves like quick attack. This Pokemon will likely by a water type but it is shown using psywave in the video as well, so perhaps it will be water/psychic.
The fourth Pokemon is Vikavolt, it is unconfirmed but this appears to be Grubbins final evolution having broken out of the shell that is Charjabug. It follows the theme of the Bug/Electric type. It uses an attack at the end, whether this is new or a returning move is currently unknown.
Fifth is the Pokemon Cutiefly, based on its appearance it looks like it could be a Hummingbird Clearwing Moth. It uses Fairy WInd in battle so a possible type could be Bug/Fairy or Fairy/Bug.
The sixth Pokemon shown is Drampa, it appears to be a mix of a Chinese Dragon and the Loch Ness monster. It will most likely be Dragon Type. It has an old appearance so maybe it is a combination of Dragon + Grandpa? It uses the move Dragon Breath.
The final Pokemon is one that is mentioned in the gameplay demo from the Nintendo Treehouse. This is the legendary Pokemon Tapu Koko, it is said to be the guardian of the first island 'Melemele'. It has a very Hawaiian Totem look to it to add to its Guardian status. Based on the video it appears electric terrain could be in play, so perhaps it is some form of electric type. There are three other guardians mentioned for the remaining islands, so this Pokemon will be joined by others eventually.