OK, about these pictures. I admit some of the Pokemon can be random, but it's obvious there has to be spoilers hidden too, as many of the Pokemon we see match with captures made by both, Ash and Goh. Some others also make reference to Koharu and other characters.
1º) Let's start with the tiny image:
+ Pikachu, Darkrai, Cresselia and Sirfetch'd: No need to analyze.
+ Sinnoh's Starters: Goh already captured the three starters from Galar, so maybe these will be distributed between Ash, Goh and Koharu. Ash will get the one he doesn't have, Piplup. Turtwig and Chimchar could be with Goh and Koharu. Since Grookey doesn't seem to have a fighting style, maybe Goh will get Turtwig.
+ Luxray and Shinx: Luxray can be a reference to Volkner, and personally, I would like Ash getting a Shinx. Not only because that Luxio he befriended back in Sinnoh, but also as a reference to one of his journey partners, Clemont.
+ Rolycoly, Carkol and Coalossal: I want to see this as a potential capture for Ash. Especially remembering the Coalossal he protected from the mad people during the Eternatus' arc.
+ Galar Ponyta: I wanted Ash to get this Pokemon too, but I guess it means Koharu will be the one to get it.
2º) About the bigger pictures, the first one is clearly a promo for the remakes of Sinnoh, with all the Pokemon from that Generation. Even so, it could have some clues, like maybe Goh's Misdreavus evolving to Mismagius. The second one, however, MIGHT have hidden spoilers of future events, considering many of them are between the ones that are already regular in the anime. I'm going to mention the ones that call my attention the most:
+ Kanto:
- Pidgeot: I hope this could mean the return of Ash's Pokemon.
- Butterfree: Yeah, yeah, I know, it can be Goh's, but since it doesn't have much role in general, can you blame me with dreaming about Ash's Butterfree returning?
+ Jonhto:
- Tyranitar: Definitely, Ash's Larvitar returning and evolved.
- Starters: I would like Ash's would return and evolve further, especially Totodile.
- Togepi: Ash found Togepi's egg originally, and Togetic can use Aura Sphere (Aura Power) just like Lucario. So, why not?
+ Hoenn:
- Torchic: I would like Ash to have a Blaziken too.
- Metagross: I don't know why, but I always this Pokemon as one potential capture for Ash.
- Corphish: Ash's could return? It would be a good time to make it evolve to Crawdaunt.
+ Sinnoh:
- Empoleon: The Sinnoh starter Ash is lacking. He has to catch one.
- Shinx: Another potential capture for Ash.
- Garchomp: it could mean Cynthia's return, but I would like Ash's Gible returning and evolving.
- Mime Jr: Someone (Ash, Goh or Koharu) could get one and evolve it into a Galarian Mr Mime and then into a Mr Rime.
+ Unova:
- Starters: I would appreciate the return of Ash's to make them evolve.
- Gigalith: MAYBE Ash and Goh will make their respective Boldores to evolve by trading.
- Zorua: Another good capture for Ash.
+ Kalos:
- Tyrunt: Ash definitely needs to capture one of these.
- Pancham: Another potencial capture for Ash, as reference to Serena.
- Litleo: Ash befriended one in the past, so it could return.
*Greninja: It doesn't appear here, but Ash's Pokemon definitely has to return.
+ Alola:
- Rowlet: I would want Ash's returning getting rid of the Everstone and finally evolving.
- Toucannon: I have doubts about this one for Ash. I don't know.
- Vikavolt, Turtonator, Alolan Vulpix: I know they can be references to the Pokemon of Ash's gang, but Ash could still have one of them for himself. Vikavolt and Alolan Vulpix the main ones.
+ Galar:
- Orbeetle: This is the only one I see fitting for Ash.
