>>34782255OP is trying to resolve a plot hole in the games. You're just going insane. Your headcanon is shit, no one cares.
The Pokédex makes a bit more sense if you do like, a soft retread of how you consider it – we take the internet and shit for granted now, but it's entirely possible for a professor, working on his own, with the grand idea of cataloging every single animal in existence into a virtual PDA, to start listing them off 1-150 and when someone points out 'hey, prof, you forgot Houndhour and Houndoom' to just think to himself, "oh, fuck. I'll put them in the next update."
Problem is he keeps saying 150 Pokémon have been discovered, which you can dismiss as him being a braggart trying to promote his Pokédex, but then it's just autistic headcanon.