Some info on story and on gameplay.

Evil team is: Team Nova

One if your rivals is from team Nova
They are constantly in your way as well.

Team Nova's goal differs per version.
In sword: travel back in time and fight back in the great pokemon war.
In shield: travel back in time and defend galar in the great pokemon war.

Multiple endings
Ex: Nova rival may be champion

Towards the end of the game you travel back in time with team Nova and catch the legendary *differs per ending* Legendaries are two DIFFERENT wolves that appear to be like hybrids with other animals,

New ability: stat scope.
This allows you to analyze a pokemon stats in battle.

No armor evolutions, but there is a new mechanic tied to galarian royalty.

No galarian forms, but there are new branched evolutions for older pokemon.

Two professors, one studies new mechanic, other studies branched evolutions.

That's all I have right now.