I’m a VFX artist that received a job with Game Freak in 2019. I mostly work on particle effects and because of that I know a lot for gen 9. Here’s some of what I’ve acquired.
>another dex cut (about one half of the Galar Pokemon won’t arrive to gen 9)
>gigantamax and dynamax removed
>new battle mechanic involves Pokemon dancing and singing as they battle
>dancing has a defensive effect and singing has an offensive effect (I don’t know the details)
>you collect instruments throughout the game that unlocks to player new dances and songs
>"music clubs” are buildings in many towns akin to the old game corner but with rhythm mini games instead (there are techno remixes of gen 1 music for this)
>100% open world (but it’s not seamless like BoTW)
>there’s a town built entirely in a crystal cave underground
>large ocean paths akin to Hoenn-chihō
>Meloetta is a big part of the story
>there will be about 50 new Pokemon
>fire starter is a goat, it has blue eyes
>large bird with tree branches for wings I saw in art (looks like a legendary to me)
>purple frog made of mushrooms was seen in a forest
>gyms are still regular gameplay once again
>one gym leader is a muscular rapper for steel type
>another is an old man with a flute as a psychic type gym leader
>there is also a beautiful gothic style female (I don't know what type of gym, maybe ghost or dark)
>Azami/Lucy returns from gen 3 as her friend
>might be the first main Pokemon game to be rated CERO B in my opinion (E10 equivalent for Americans)
I don’t know what the new region is or what the titles are. No voice acting and no new sound type. I’ll try to stick around for an hour or so to answer any questions. Also a couple of these things are purposefully false so I'm safe.