So...I'm sticking mainly to the core series games, barring Sword and Shield (and the upcoming BDSP and Legends), because I am not much of a spinoff person, but let's run down the list, shall we? This is my personal ranking of the mainline games thus far, and here we are. Yes, the way they are listed from left to right is a ranking from most liked to least liked. And some short explanations for each:
S:
BW2: My favorite Pokemon games bar none. BW2 is not as good in the storytelling department as its predecessor BW1, but it picks up off the original nicely and it expands on Unova greatly, all with some great new characters and more places to visit to expand the region from its original BW1 iteration. There's so much to explore and do in the new Unova, a great variety of Pokemon to use on an in-game playthrough, and the game is just plain fun with a solid level curve and goes out with a bang against Champion Iris. Plus there's so much stuff to do in the post-game, so much more to explore, PWT, White Treehollow/Black Forest, many legendaries to find and catch. The game is ripe on content and is so much fun.
Platinum: Another close favorite of mine. Improves upon Sinnoh greatly with a more vivid and distinct aesthetic, and the adventure is fun not to mention the story is pretty solid for a Pokemon game, not to mention Sinnoh's lore is very compelling. The Gym Leaders, E4, and Champion are fun to battle and exploring Sinnoh is a blast, and unlike in DP there's a reasonably good variety of Pokemon to use. Best part about this game, however? The content. Absolutely the content. Super Contests, Pal Park if you wanna transfer mons from Gen 3, the Battle Frontier, the Villa, and Gym Leader/E4/Champion rematches all upgraded, and Barry rematches too. The game is right up there with tons and tons of features and super fun gameplay for a DS game.
HGSS: While super flawed, they are fun. Level curve still sucks ass and the mon variety isn't great, but otherwise outside of the tedious old school grinding needed due to a jank level curve, the game is fun in all the features it has. Pokeathlon is a fun minigame, you get to explore Kanto and this time meet some legendaries there (after GSC Kanto was pretty bad and barren), Gym Leader rematches and E4/Champion rematches too, and all in all it's a very nice looking game. I also love the little things like hearing water when you're near the water or your own walking and whatnot to make the world feel more alive, and Johto looks super pretty in this game. Walking Pokemon is kind of a meh feature, but it has its moments and it is fun to have them around with you every now and then.
USUM: Storywise, they are not as good as SM, but it's not totally bad either. Best of all is that this is the one Pokemon game that is truly what I'd call challenging. The Island Challenge in USUM is much better, with better Totem bosses who have great movesets, clever use of items, and use SOS partners that synergize with them well to make for truly compelling boss fights. Not to mention Mt. Lanakila is a proper Victory Road this time around! The characters are all super memorable, and not to mention this game is just very fun to play through as a truly challenging Pokemon experience. When it comes to added features, it's not as good as Platinum in that regard, but USUM does have its share of content with a fun post-game Rainbow Rocket episode for the shoutouts to old villainous teams, Ultra Space while small in scope allows you to catch lots of Legendaries and whatnot, and Mantine Surfing can be pretty damn fun. I think it'd be better received if it didn't come so soon after SM and/or it was one version instead of two, so business wise it wasn't a good practice, but when it comes down to it it's still an incredibly solid game in a vacuum.
A:
Emerald: It's Hoenn but better than RS!!! I have to rate it lower than Platinum or USUM but it's not bad. It paved the way for Platinum by introducing Gym Leader rematches, more post-game content with the Battle Frontier, which is fun, and a post-game rematch with Steven. The magnitude of content is not that much but it's fun. And it does well in combining Magma and Aqua's roles into the story and having you take both of them down. The execution is not so great with the Gym Leader rematches and whatnot, but it's still a very good game in its own right, and frankly, despite it being a Gen 3 game, it's the game that carries Gen 3 even if RS and FRLG were both good games.
XY: The first entries in the main series that were 3D, and boy were they hype! I know this game has some flaws, but it's very good. Mega Evolutions were hype as fuck. Seeing the Kalos region was a beautiful sight, and boy does it take advantage of the 3DS's capabilities. Pokemon Amie is such a cute and fun feature that allows you to play with your mons and interact with them, and so many of them look so adorable! The three minigames that come with Amie (Head It, Tile Puzzle, Berry Picker) are all super fun to play as well. Super Training is also a fun way to EV Train your mons. The story is fine, even if it didn't reach its full potential but it has its moments, and it's a solid journey all in all, while being a brisk, simple game not bogged down by railroading or cutscenes. The Pokemon variety is incredible though! So many mons, and this gives XY immense replay value because there are so many mons you can use that every playthrough feels different, and the game is also conducive to many challenge runs or unconventional runs and that's what also makes this game so fun to revisit every time I want to. Lumiose City is also a beautiful city all in all. Not a perfect game, but a very good Pokemon experience that is relatively simple, but good fun.
ORAS: Despite the disappointment in a few areas, it's a great remake of RS. It does a great job in fleshing out the characters and story of RS to make them more memorable than previously, and the Delta Episode was a fun post-game story too that ended with a bang with the Deoxys vs. Rayquaza showdown and it was a great adventure that really takes advantage of the 3DS to reimagine the Hoenn region in much greater detail and life than previously in RS. New Megas were awesome to have as well. Not to mention Contests and Secret Bases are back and better in ORAS than ever. And I HAVE to talk about Soaring in the Sky, because my god that was so, so good! Flying on Latias/Latios and seeing Hoenn from a sky view was a sight to behold! It has everything great about Hoenn and a few great things about XY added to it to make for a solid Hoenn experience, great game all in all.
BW1: BW1 is part of my favorite generation of games but BW2 is what gives Gen 5 such an edge imo. It's an awesome game though: the story is very strong, the new mons are fun to use, and I love the characters and this really makes for a bona fide RPG experience, one of the closest ones Pokemon has gotten to being a bona fide RPG thus far. The only reason I rank it lower than the things above though is the relative lack of content. Aside from exploring eastern Unova...this game's rendition of Unova is a bit barren and there's not a whole lot to do, even if it does have a reasonably decent post game.
SM: Likewise, SM had a great story to tell and despite it being so railroaded, which is why I rank it below BW, it's a great experience. The Island Challenge isn't as good as USUM's, but Lillie's story in SM is very touching and I loved seeing her change into someone who is more independent and able to stand her ground over the course of the story, while the player does the Island Challenge and eventually ascends to become Alola's first Champion with a grand showdown against Kukui. It's such an awesome game, and while it's not as good content wise or challenge wise as USUM is, it's a good game all in all, and I was very happy with the experience.
B:
FRLG: They're good. Sevii adds a nice post-game which was good precedent for Gen 4-5 post games Battle Zone and Eastern Unova, but aside from that they're basically the typical Kanto experience. Except they just...kind of exist, and that's it lol. They have some nice improvements like the Vs. Seeker for easier and more fun forms of grinding, and Sevii, and all that jazz, making them good games overall. They're just not as good as the stuff that came after.
RS: Excellent debut for the GBA, with excellent animations, gameplay speed, and a good adventure to play with lots of awesome mons. Not to mention some neat features. Emerald and ORAS are both way better than RS, but RS by themselves are super solid and even if you took both ORAS and Emerald out of the picture, they're solid games, albeit barebones with minimal post-game content.
Crystal: Only gets a slight edge over GS since what it added wasn't much, but it was a pretty good Johto game with a slightly altered story and a few things like the Battle Tower.
DP: Infamously bad issues aside like the small dex, weak level curve, and the game being slow as molasses aside, it's a good game. It has most of what makes Sinnoh as good as it is, just not nearly as polished as Platinum.
GS: Super nice games for their time, but have not aged well. Johto is nice in the Game Boy aesthetic and the game is good fun, but Kanto is barebones here and the level curve sucks ass. They are good for what they were in their time though, albeit deeply flawed.
C:
RGBY: Gen 1 as a whole has not aged super well. The games are bugged as hell and they are very primitive compared to the games that came after, and as a whole in the present day they are barebones Pokemon games. That being said, I still respect them for being the debut of the Pokemon series as a whole and they are still well, good games for their time, and even now they are worth playing as a fast and fun retrogame experience and the bugginess does have its own charm.
Never Played:
LGPE: I've never played this game because I straight up don't think this game is for me. Maybe one day used, but eh.
Just a long rambling of thoughts here lmao.
As for Sword and Shield, I would probably put it around lower B or higher C without the DLC, and maybe higher B or lower A with it. The DLC redeemed it by adding a load of great content plus two great Wild Areas, but in the end, it's still DLC and the base game is pretty deeply flawed, even if the game is overall pretty darn fun. BDSP I would probably expect to be around higher B tier at least in my eyes, but I'll have to play it when it comes out first. Legends: Arceus is uncertain, but I have hopes it will be an A Tier game with the likes of Gen 6, Emerald, BW1, and SM at the very least, but I hope it'll be a high tier Pokemon game and I do greatly look forward to Legends.
