When it was good it was very, very good but when it was bad it was fucking terrible.
That sums up Generation 4 in one bastardized nursery rhyme with unnecessary swearing. Generation 4 included a set of amazing remakes and some of my favourite Pokémon of all time but Diamond and Pearl were plagued with issues and included the likes of Purrugly and the Lake Guardians. Very little, be it games or Pokémon fall into ‘just alright’ category and for me (and it seems for many others) the bad overpowers the good in our memories, because Platinum was a far better game and looking at the scores there’s a lot of 4 to 6 ballers leading me to the conclusion that it isn’t the Pokémon per-say that’s the issue but the types of Pokémon (not Elemental Types) and their distribution in the original game that soured me (and seemingly many others, certainly those who edit TV Tropes). I hate accusing Game Freak of being lazy because I know they’re by and large not but it really did feel that if they weren’t being a bit lazy they were certainly playing it safe – and got the response they deserved for doing so: building the new Pokémon around cross-generation evolutions (which had typically been well received in Gen II and could get ‘the rub’ from earlier ‘mons with established fanbases and/or nostalgia) and the always-popular Legendary and Mythical Pokémon with little else but the standard types of Pokémon every region needs (common bird, rodent, fish, bugs, Starters, Fossils). And of course it completely failed, the Cross-Gen Evos were mostly divisive or rejected and fans become oversaturated with Legendaries, sapping them of their specialness and their role as guaranteed hits – in an attempt to rely on something they took away the ability to rely on it. The derivative designs of the Starter Pokémon only made the feeling that this was the ‘playing it safe Generation’ even stronger, I don’t for a minute believe no-one noticed and it as a complete accident, these things are opinion-polled to tedium within Game Freak, someone would have pointed out ‘these are just Bulbasaur and Charmander’
And then there was the aforementioned distribution of these new ‘mons in Diamond & Pearl, the first games in the generation, our first impressions of it. Some of it was a simple result of the types of Pokémon that dominated the new ‘Dex, most Legendaries typically being available only in the post-game and most Mythical ‘mons being Event-only and so not available to most players at all (especially when the Arceus-centric event was never held), Fossil Pokémon are typically one per game and Baby Pokémon mostly are only available through breeding (Gen 4 actually changed this up, Munchlax and Budew are catchable) so I shan’t hold that against the team (though it doesn’t help) but the decision to keep most of the cross-generation evolutions to the post-game I totally will, as will I hold the decision to, out of the few remaining lines they had, make two (Scorupi and Croagunk) exclusive to an optional area (The Great Marsh), two (Rotom and Spiritomb) one-per-game, one only available in a location that you had to travel back only on one day (Driftloon) and two, including a hyped Baby Pokémon (Munchlax) only available through the Honey mechanic. Meaning that players could miss even more of the new Pokémon and thus the regular routes felt even more dominated by old species older player were growing sick of or the same old region-specific com mons. It was a string of dumb decisions that added up to one of the least satisfying Pokédex in the series BEFORE the lack of Fire Types. The game added 107 new Pokémon but it sure as shit didn’t feel like it.
Away from those games though? The Pokémon are at least mostly ones I have strong opinions on and frankly I’d rather that than a load of meh ‘Mons like I’m expecting in Gen V.