>genwun
The genesis of the series, badly made, but arguably excusable. There isn't much else to say about this one; it would probably find itself in the middle or middle-low portion of anyone's list.
>gen 2
Well-made due to Iwata stepping in during development. Large overworld, good amount of freedom and good amount of story for its time. Pokémon variety is nothing special and it's a bit annoying that a lot is exclusively post-game, but it's not objectively bad or anything. Actually very good, even.
>gen 3
An overhaul that was very controversial. No connection to previous games and a lot of new directions for Pokémon designs. Started the pattern-rich development style of the next 3 games (with starter patterns, game release patterns, legendary patterns, evil team patterns, etc) and was fairly mediocre overall. Not objectively bad by any means, and still pretty fun to play even to this day.
>gen 4
Basically a rehash of gen 4 in story and premise, but with fewer Pokémon, fewer interesting ideas (for example, only one evil team this time, but no interesting version-exclusive gimmick to replace it with) and the largest shark-jump in all of jumping the shark history with regards to Pokémon, by introducing Literally My Mom's God and his Pantheon Friends in one fell swoop. First gen to be created poorly after gen 1, the games were exceptionally slow and had the single worst regional dex ever created (DP dex.) So bad that they had to put out the third version as basically an update, and it still didn't fix all the issues present. Additionally, this gen turned off a lot of the previous fanbase despite selling very well, and caused in part the commercial failure of gen V. HGSS are excellent entries though, only building on the already very good GSC.
1/3