I know this is a bait thread, but...
>kanto again again again
>starter is the most kid-ified the game has been. perfect, high bst, extremely broken moves
>new content limited to mega access, go connect, and alolans / melts
>catch system is VERY bad, excellent almost necessary for anything over Lv30
>legendaries are 10% battle, 90% swivel system and aim
>no quick buttons for items you need
>chains mean the sky is filled with dragonites and charizards, so little variety in 'rare' spawns
>shiny rate is badly programmed, only applies to next spawn in chain then breaks until another successful catch
>1 on 1 match battles give meaningless titles, no real bonus
>1 on 1 match battles are a PAIN, as they have the best counter moveset so you have to too
>NO FUCKING WAY TO FEED MORE THAN ONE CANDY AT ONCE IS AWFUL. GODDAMN AWFUL. Have fun pressing A 300 times
>lag, programming fails so 10+ spawns can stutter consistently
>no QoL improvements beyond what FireRed already did or was simplified for kids (aka key item changes)
>skippable cutscene option, only applies to 5 of the 20+
That's top of my head. I played, but I did not enjoy.