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Having a limited roster of Pokemon available in the mainline series games is a totally acceptable way for Game Freak to manage the ever-increasing roster of Pokemon each generation.
As well as keeping the competitive meta fresh, it also allows better balance between new and old Pokemon and prevents fangame-like oversaturation (like what happened in XY with what felt like 20 new Pokemon every single route).
However forcing players to pay not just for a centralised storage option, but to transfer their Pokemon AT ALL, is absolutely not okay. Bank was fine when it was just an optional way to extend your boxes that most people would never need beyond the initial transfer from HGSS/BW -> Gen 6. But Home is literally a racket.