INCOMING OPINION
So this is about favorite games, huh? Well that's hard, but my favorite gen was 4. Hands down, no contest. And don't you dare say I'm nostalgia blind, cuz technically I started with Gen 3 and my first pokemon was Minun. Points to whoever can figure out what game that was. My first main series game was Platinum, and oh lord did I love it. Unfortunately with gens 4 and 5, you either love it or hate it. I love gen 4, think gen 5 was crap for the most part. Before you start gathering your pitchforks and torches, hear me out. I'm talking about both gens as a whole. That means main series and spinoffs. It also only includes what I've played, which is pretty much everything but Conquest. I heard that it was pretty good though. So let's start with why I like Platinum.
1) The music
So I'm a really musically oriented person. Music has a huge effect on me and the game. With Platinum, the music was very enjoyable. I liked pretty much all of them but the generic legendary theme, which sucks in BW too. Actually this is the opposite of gen 5 for me. The routes' music was amazing, the rival battle theme was fitting, and team galactic's theme was boss. All the battle themes were excellently done, and the area themes too, but that's enough gushing about that.
2) The evil team
I love team Galactic for the same reasons I love teams Aqua and Magma. Their goal. In all three cases, each team wanted something extreme and would do whatever it took to get it. In DPPT's case, it was stuff like blowing up the lake, kidnapping and almost killing the lake trio, that poor guy in the Valley Windworks, etc. They also almost accomplished their goal by summoning said legendary. In platinum, it got so out of control that a literal God had to step in. And it's dark enough to be enjoyable too (ever notice how Cyrus never makes it out of the Distortion world?).
3) Pokemon and designs
Like #1, this is pretty much the opposite with BW. The designs and concepts were good for the most part. Gen 4 was the last gen (excluding Sylveon) to give old pokemon new evolutions. Togekiss, Magnezone, Glaceon. Of course, the good comes with the bad, and I will not ignore the fact that gen 4 has flaws, like every other gen, but we'll get to those later.
And where do I start with the starters? They're all good. They all have counters for each other. Infernape has Fire for Torterra and Fighting for Empoleon. Torterra has Ground for both. And Empoleon is capable of learning ice moves to ruin Torterra (and flying, but why would you do that?).
4) Areas and atmosphere
MOAR MUSIC
nah, this is more about the maps. Every map had it's own feel to it. From the Lively, adventurous feel of 205, the serene, peaceful feel of Eterna forest and the 210? area (with pokemon mansion and pastora city. It's been a while.) the intense climb up Mt. Coronet and the dark, dangerous feel of the Distortion world, this game had arguably the most varied enviroments.
5) The characters.
This is a mixed bag really... As far as gym leaders go, most of them are forgettable in any game. Especially gen 6. 5 wasn't that good either... But characters like prof. Rowan, Lucas/Dawn, the rival, and Cynthia were very well done. I saw a complaint about lack of character development, but that really depends on how hard you look. If you really explore everything, you can get a lot more information than if you just rush through the game. Even the gym leaders get quite a bit. For example, in the Villa, or by talking to other npcs, you get a lot of information. Also events. Those are last. Platinum also does a great job with implications. Cyrus'childhood is an example.
6) Events and post game
So I didn't really play Diamond or Pearl, but since platinum is their successor I see no need to focus on them. It's different with BW/B2W2, since those are sequels, continuations of the story.
Platinum had a crazy amount of small events and sidequests. There was stuff like the Iron Island thing with Riley. Stark mountain with Buck. Even Victory road with Marley. There was Mira too, in that cave under cycling road. I'm 100% serious when I say you need to check everything. The mystery gifts were amazing also. Rotom was a nice little thing, but the Secret Key and Oak's letter were by far the best mystery gifts ever. They added new story and even areas to the game.
As far as post game goes, Platinum falls short to only HGSS, and that's because there was another region in those. You have the Stark Mountain arc, the sidequests, underground, and a plethora of legendaries to catch. Don't forget the battle frontier either.
And now, FLAWS.
As good as the game is, there are flaws.
Let's go in order.
1) Generic legendary battle music was generic. It was uninteresting, really. But that's more than made up for with the other themes.
2) I got nothing. The team was great. Although they seemed to be silly at first, they quickly got their act together.
3) Okay, so we have the good, the bad, and the wtf is this. Most of them were good, but stuff like Hippowdon, Tangrowth, and God forbid Probopass are a thing. Ugh
4) Ha! The only thing wrong with this is the fact that you can't revisit the distortion world in its entirety.
5) Some gym leaders were good. Then some weren't. Lookin at you, Gardenia. But Candice, Wake, Roark and Byron were just fine. Maylene was...meh. They each had character, except for the garden freak. Idk what she was doing.
6) The only issue here is that mystery gift isn't available forever. Apologies to those who didn't get to do the Shaymin event. Go buy an Action Replay.
Dear god this is long, but there's still more. Spin off time!
So my favorite game is a tie between this and PMD: sky. Why? Sky has amazing story, good music, and lots of content. Nuff said. The Ranger games were a fun little thing too. Gen 5 brought a lot less to the table.
(Pokepark sucks in both gens.)
And now for why Gen 5 is my least favorite. It's pretty much the opposite of gen 4 for me.
1) Music was meh. Really, there weren't many outstanding tracks. Route 10 is pretty good, entralink is amazing, N's castle bridge was good, Hugh's theme and team plasma grunts were catachy.That's about it. The legendary themes were ass, Ghetsis was literally just drums, N was ok, Rival's wasn't that good. At least not for cheren.
Black city was beautiful too. Almost forgot.
2) This is a mixed bag.
Their story was interesting. Their true motivations and actions were a cheap rerun of team Rocket. Especially in B2W2, when they were more overt. I do like the climax of BW though. Except, you know, music. God it's awful.
I loved Bw2 because of the extremes they went through. You know, freezing the region.... That was good.
3) Designs and pokemon were an all time low for the series. Some seemed reused, some were plain, some were good. Of course we have Garbodour and the ice creams, but there's also the Fire/fightimg pig and Emoga the flying Pachirisu. And for Christs sake, wtf Unfesant? And the elemental monkeys, and the list continues. I liked a fair amount of them. Serperior, Krookodile, Volcarona... The legendaries weren't all that either. Swords of justice were ugh. I really liked the idea of Reshiram and Zekrom being fused with Kyurem though.
4)
This is the part where I start asserting the redemption bw2 brought. Allow me to remind you about how you can't access a good chunk of the region until post game. And after that, there's not much to do there. As far as maps go... I don't really remember a lot of the routes. Forgetable.... N's castle wss cool. That's it.
5) Characters
So now you're gonna want to shoot me. I welcome it. Like I said earlier, gym leaders were Forgetable (like many other gens). I only remember Marlin because he was so badly done. Iirc, he doesn't care about team plasma at all. And remember Brycen? Cuz until a few days ago I didn't. Anime was soooooo bad. I actually stopped watching because of it. N was really the only in depth character we get. The champions are embarrassing to say the least... I'm done.
6) Again, bw2 saved gen5's ass. While there was close to nothing in bw, bw2 brought more exploration and legendaries. It was great. BW? Not so much. I hope you enjoy diving. As far as mystery gift we got, what, Victini?
And now, spinoffs. I don't even like mentioning PMD: GTI. it was the only game I wasn't upset to lose when I lost a bunch of games. It's like a lot of gen 5, pretty decent until you compare it to the other games. Then it's god awful. I think Conquest is the only other game besides that, but I heard it was pretty good.
There were some cool things about gen 5, like seasons and HAs. They aren't terrible games, just my least favorite. Could have been better.
Side note: this post is probably full of errors. I spent an 1 and a half writing this on my phone. Ugh. Also it's crazy long. And more rushed towards the end. Oh well.
TLDR: You wish, I'm too tired. Its 3 am. Read it, I dare you.