The Pokémon formula has remained largely unchanged for 20+ years and Nintendo seems resigned to the mantra that if it ain’t broke don’t fix it, and Pokémon is still making money hand over fist. There are still 3 starters, there are still 6 Pokémon slots in your party and there are still 4 move slots. And there are still 8 GYM’s, Sun and Moon may have tangentially diverged from the GYM formula, but the upcoming Switch titles are returning to the unchanging formula. Complaining about these similar elements in every game in the franchise demonstrates to me that you’ve missed the point of Pokémon, and that’s the creatures themselves. The Pokémon, in Pokémon are the main draw. The designs of the Pokémon are consistently good, (there are some outlier terrible designs and there is a tone of awesome, imposing creatures) and the typing system itself breeds creativity. But the seer amount of Pokémon in each game make the games individually infinitely replayable and it’s a genius formula on Nintendo and Game Freaks part.
There are a shit-tone of Pokémon, more than 700, and your different Pokémon playthroughs hinge entirely on your choice of party members, therefore Pokémon urges its player-base to return to the games and try again with different combinations of Pokémon. And that’s the genius of Pokémon from both a design and commercial standpoint, infinite replayability and lack of burnout due to each playthroughs uniqueness equals a whole lot of cash. If you choose Charmander on your initial playthrough, players then want the perspective of starting with the different starters and replay the games with Squirtle or Bulbasaur as their leads. New Pokémon games will continue to sell because more Pokémon introduced means more possible combinations and new alterations to the sprawling online meta. Pokémon is infinitely replayable and its genius. If Nintendo and Game Freak can keep churning out these games with new creatures, they will have a well-oiled money-making machine forever.