I know I'm several pages late, but I'm gonna write what I liked and disliked about each Pokemon generation like Opo did.
R/B and FR/LG
+ First game in the franchise. The franchise wouldn't have existed without it.
+ Mostly good Pokemon roster with few duds.
+ Good starter trio.
+ Good soundtrack.
+ The twist of the champion being your rival was a nice twist.
- Really sluggish to the point of being near unplayable. (FR/LG fixed this to a degree)
- Game looks ugly, even for a Gameboy game (FR/LG fixed this)
- Game breaking glitches that listing all of them would take eons. (FR/LG fixed this)
- Type matchups were confusing and didn't work like they do now. (FR/LG fixed this)
- I personally really disliked the non-linearity of the game. It can be confusing as hell sometimes.
- Underleveled wild Pokemon make for some hellish grinding sessions. (FR/LG fixed this to a degree)
- Poke Balls can miss. (FR/LG fixed this)
- "Come on, come on... UGHHH.... This would've been so much easier if I could just BATTLE these Pokemon!!! Why, Safari Zone!? Why have you condemned me to this Pokemon prison!? Why do you despise the art of the capture!??? I can't.... I CAN'T.... I CAAAAN'T!!!!!"
- You have to save your Master Ball to the Legendary Beast in the remake because of that Roar glitch.
- No post-game aside from Mewtwo (FR/LG fixed this)
- I have a personal nitpick with both the original and the remakes, and that is the lack of physical/special split. I know why they weren't included but it makes the game near unplayable for me... Though, R/B were already unplayable for me without that. It doesn't help that no version of the game that includes the split exists, and it probably never will.
- FR/LG felt more like a simple graphical update than a remake to me.
G/S and HG/SS
+ Good soundtrack.
+ Scizor, Ampharos, Crobat, Tyranitar, Heracross, Skarmory, Houndoom.
+ You can explore two regions.
+ Shiny Pokemon.
+ You can dress up as a Team Rocket grunt for a short time. (HG/SS)
+ Pokemon following you in the overworld. (HG/SS)
+ Good post-game. (HG/SS made it even better)
+ Steel and Dark types.
+ Time based events are a cool concept that makes the game feel somewhat more realstic than its predecessor.
- Worst starters in the series, with Cyndaquill being the only one I consider to be okay-ish.
- Introduced roaming legendaries, which were annoying to deal with back then and are still annoying to deal with.
- Underleveled wild Pokemon in Kanto make for some akward grinding sessions.
- I literally gave up on getting all of my Pokemon to the same level as Red's Pikachu.
- Relies way too heavily on the Kanto games, which makes it feel very vanilla in general.
- The Pokemon roster also feels very vanilla due to there being so many evolutions/baby versions of Kanto mons.
- Most of the cool Johto mons are either really hard to find or aren't available until the post game, with most of the Pokemon being from Kanto. (HG/SS fixed this to a degree due to the Safari Zone being a thing and it's a lot less terrible than the Kanto version)
- Said cool Pokemon are also really underleveled when you find them in the post game.
- Johto is small and forgettable.
- Unown.
- Lore is only explained in events IN THE REMAKE.
- The entire Sudowoodo thing is a pain. If you forget the squirtbottle, you have to backtrack aaaalll the way to Goldenrod, which guarantees some wild encounters in the way if you don't have repel. Then there's the matter of fighting the beast which is a pain in the ass and made it one of my least favorite Pokemon ever.
- There's also the matter of what it takes to get it... *PTSD flashbacks of Whitney's Miltank kicking my ass*
- Stantler is way too common and can be annoying to fight against while grinding.
- Some of the cool Pokemon that are found in Johto can be annoying to find at times. The Bug catching contest's encounter rates in Bulbapedia are super inaccurate.
- Like the Kanto games, G/S is hard for me to play due to the lack of physical special split (HG/SS fixed this obviously)
- HG/SS has an absurd amount of HMs and you need almost all of them to get to Red.
R/S/E and OR/AS
+ Feels a lot more varied in terms of locations compared to its predecessors.
+ TRUMPETS (OR/AS removed it but they still had a good soundtrack)
+ Starters are amazing.
+ I actually care about all of the cover legendaries.
+ Metagross, Salamence, Gardevoir, Breloom, Manectric, Swampert, Sharpedo, Aggron...
+ Steven is cool.
+ Wally's arc. (OR/AS)
+ One of the gym leaders is your dad.
+ OR/AS Archie and Maxie are great.
+ Introduction of abilities and natures.
+ Great post-game. (OR/AS)
- Too much water/10
- Some of the Pokemon feel rather forgettable, imo.
- Should be predictable by now, but I can't really play R/S/E anymore due to the lack of physical special split. (OR/AS fixed this)
D/P/PT
+ PHYSICAL. SPECIAL. SPLIT.
+ Staraptor, Luxray, Lucario, Infernape, Floatzel, Garchomp...
+ Some great new evolutions of old Pokemon such as Roserade, Magnezone, Electivire, Gliscor, Mamoswine, Togekiss and Weavile.
+ Starters are neat as well.
+ Soundtrack is great, as expected.
+ Ghost type legendary.
+ Cyrus is a great villain.
+ Cynthia is the best champion. That is a fact.
+ Barry is neat.
+ The game is actually challenging at times.
- I actually dropped Diamond because it was so slow.
- Waaaay too many HMs.
- Regigigas.
- Probopass.
- The Haunter trade. I actually did it without knowing what's going to happen.
...and that's it for now because writing all of this is pretty exhausting. Stay tuned for part 2.