I mean, no one has an automatic right to sell a lot of copies. The fact that AAA budget games often sell less than Pokemon mostly just means that they need to adjust their budgets downwards according to their real sales potential. No one would scale up the budget of a game if it can sell AAA amounts of copies on a lower budget, its a business after all.
Pokemon became a mega franchise already back in the 90s with the first game, made by a very small team and ran on hardware that was very antiquated at that point. Budget and presentation has never been what made Pokemon big, which is why it isn't comparable to say Final Fantasy which only got big from FF7 and its high budget and solid presentation, which led Square Enix to need to chase ever higher budgets to keep up the presentation level it needed to sell big numbers. Pokemon never had that issue due to getting big from entirely different aspects than graphically looking good.







