I enjoyed playing Pokemon red when I was younger, and was immensely disappointed when playing Pokemon Diamond.
It was the same game, with 1,000 gimmicks and side shows tacked on - the Underground, Secret Bases, Dress Up & Accessories? Am I meant to be glad I didn't get the copy that had phone call spam from a braggard with a Rattata as a feature?
The graphics had gone from acceptable at the time of release (Red) to rather shoddy actually (Diamond). When the number of pokemon's rocketed up, the size of the project to animate them (so they look like something other than bouncing pixelated cardboard cutouts making screeching noises) shot through the roof. The sprite sheets from Streets of Rage 2 characterise the minor thugs better than event pokemon from a RPG released from nearly 2 decades later - even allowing for what is essentially pallete swapped shiny pokemon.
This is not a stylistic choice, it is low expectations on the players behalf. Pokemon's business model creates bloat - or really just a "here we go again!" ending - and this is a sign of a project choking under its own weight. Even rare or specific flavour animations don't exist. When two pokemon that are supposedly rivals (zangoose v seviper, for example) are brought out to battle, there is no additional roaring or snarling. When a pokemon flinches, it doesn't visibly flinch. Its like a 1920s silent film, where everything is spelled out.
Any attempting roleplaying in a game as linear as Pokemon is bathos. This is a show where even where the meat in food comes from has a don't-ask-don't-tell element to it. Everything is branded with the word "Poke-" in it. It is as immersive as banging your head against the outside of your locked front door and saying "I'm inside, I'm home, really!"
No actual skill can be used as an alternative for simply memorising the formulae that drive the game - the type effectiveness and weakness chart, the special abilities of individuals. Yes that's challenging, but its memorisation. There are no strategies - indeed using something like the FEAR Rattata is criticised, or considered plain cheating. Why? Because a player is no longer mechanically using the type chart and grinding to a high level to try to gain an advantage.
Pokemon Red was a great game. I will not hurt the feelings of fans of later games by insulting the sequels, but I will say this: they have been disappointments for me.