Going by what we know, it is possible that these games may not have as many as Alola. However, with it being possibly the largest region known, we could have a lot. I am hoping for 100.
With Alola, I got really annoyed by the lack of pokemon, as well as Kalos. However, in Alola, we did technically have over 100 pokemon. If you count Oricorio, Lycanroc and the Alolan Pokemon as new and different pokemon, as should be the case since they look vastly different and have different typings, other than Lycanroc, we got a total of 127 pokemon,
The only pokemon that had multiple forms that I am not counting is Minior because the forms were too similar. I am also not counting Battle Only forms such as Wishiwashi school form and Ash Greninja ect.
Because this is an even generation, I think we will see 100 at the start. However, some may be similar to Lycanroc or Oricorio, but I think we will have 100 designs.
As for pokemon, I have already named a few, but others I would love to see are these.
Folklore:
Brownie
Boggart
A number of Dragons (Possibly one line inspired by Cockatrice or a Basilisk or a 3 stage snake)
A number of Ice Types
Wyvern
Wild Hunt (But in the form of animals or something)
Corn Dolly
Mermaid or Siren
Eachy
Loch Ness Monster Legendary
Animals:
Corgi
Yorky
Magpie
Mountain Goat, I know we have Skiddo/Gogoat, but I think it could work. Or maybe a Galarian Gogoat?
Badger
Puffin
Pine Martin
Wild Boar