I have been aware that some informations posted by play testers trended so I decided to post myself more information as far as I remember.

Swanna can regional evolve to a black swam. The three looks like being ice and dark.

After Opal you face Bea who is a fighting expert, as you might know she is exclusive to Sword. Opal is not a fairy but a dark expert and she uses the female evolved form of Impidimp.

There is an angel pokemon counterpart for Impidimp known as Angelonon, it's pure fairy but I remember it can use a lot of flying type moves. While they are not exclusives, their rarity in wild changes depending on the version.

There is one gym who specializes in two types being poison and fairy. Gym leader is Nina and she uses Weezing regional form.

I could not reach anything after the sixth gym but there is a blond hair girl named Bonnie in the game who implies there is a train connecting galar to "kalos region" and that her older brother is working on it. You battle her and she uses Cllouma, a electric and flying llama alongside a Dedenne. She mix french with english while speaking.

There is a humanoid pokemon based on a troglodyte. Rock and fighting and you can get its fossil or find him on a one time raid battle. By far it is the only pokemon that comes from fossil I have acknowledge.

Keep up, there's a lot more coming