In the case of Pokémon Go, they likely use Let’s Go being developed by Game Freak as their excuse for this. If I wanted to, I could argue that both games are part of the main series canon, but this isn’t the thread for that. Game Freak never really tapped into the mobile market ever, but what I’ll be referring to as the “Go series” feels like a valid way for them to do so, even if they already had enough on their plate as a company.So I was going to say this before and went "nah thats weird" but here i go anyway: i think gamefreak likes to keep it in the family, generally
Dream Radar was made by gamefreak, so Burnett was free real estate to them. Likewise Bridgette (from Box) got to get referenced in Pokemon Ranch and brought back for Pokemon Bank.
Honestly I wonder if half the reason they periodically use Jesse & James is because they used them in Yellow all those years ago and see them as "theirs" enough in a way they don't with, like, the Rangers or whatever which were handled by different studios.
Again says a lot about their relationship with Go that they decided to debut Meltan & Melmetal, made Let's Go, allow transfers, and made a big deal about Willow getting a pokemon card....and they even get to use Jesse & James!
Most of the other popular spin-off series (Mystery Dungeon, Ranger, Rumble, etc.) are produced by... crap what’s the word I’m looking for? It’s not colleagues, there’s definitely a word for this. Anyway, those branched companies have never been involved with Pokémon outside of their own games, but when they do get involved with stuff, they live to reference their own products between games.