Just dumping this here to deflate expectations early.

-Gen V style "philosophy" based Legendaries, specifically isolationism vs expansionism, the fruit emblems are massive reference to it
-Regional dex is about the size of Alola, mostly consisting of Hoenn, Sinnoh/Hisui, Unova and Kalos. There are also new mons said to be brought over by traders and colonies in other continents referencing the Spanish and Portuguese Empires. The starters are part of this and they become a pirate, witch and priest.
-Evil team leader basically looks like pic related
-GO integration was planned but fell through
-Player characters start young for a tutorial section before a time skip to after you finish school
-No new Megas. Z-Moves or Dynamax.
-The "open world" is as heavily gated/limited as the Wild Areas
-Trainer Powers are the new gimmick. Your Dex/License can register up to three abilities you can use once per battle, you get them from Gym Leaders
-Save Data from other titles lets you get certain Pokemon earlier than usual