Least favorite Pokemon game and why?

Well, we have a thread on which Pokemon game(s) is your favorite, figured we might as well have one about which one(s) you don't like. So out of all the Pokemon games you've played so far, which ones are your least favorite, and more importantly, why do you not like them?

Probably Pokémon Diamond or Platinum. I'll say Diamond.

Sinnoh as a region didn't leave much of an impact on me. Not to mention the Pokémon introduced weren't very instant for me. A number of them have grown on me since then but I don't have many natural favourites that originated in Sinnoh.

(I'm assuming we're talking core series games? Cause if not I'd say easily Pokémon Dash)

Gold and Silver.

These games are probably the most slow-paced games I played. Seriously, these games bore me so much that the highest I can reach is the 2nd Gym. Not only that, but the story didn't interest me and I really don't like most Johto Pokémon.

I would say Crystal as well, but the only thing I like about it is Vietnamese Crystal. Best bootleg Pokémon game. x)

Pokemon FireRed/LeafGreen. This was basically due to the postgame. I found that there wasn't much to do after the game. After the Sevi islands. i found that all the other games had more to offer.

BW/BW2

Although I loved the characters, the gameplay didn't really pop like some other games, like Emerald.

Runner up: XY

These games really weren't that good gameplay wise. It was really easy compared to the older games.

Black and White. Generally, I'm not a fan of the Unova Pokémon, so being limited to only them is kind of a disappointment.

For the main games it's the Sinnoh region ones. They were just not so fun and the fight of Dialga/Palkia was so sudden with no build up of any suspense was really disappointing.

For side games I. CAN'T. STAND. POKEMON CHANNEL.
It was cool I thought because of it's looks, and now I regret not buying Metroid Prime at the mall instead.

Hm, this is a tough topic...

If I absolute had to lean against one or two, I'd say Pokémon Black 2 and White 2. While they are special in their own, unique way, them being sequels didn't quite work in my eyes (and many other people, am sure). Somehow, it seemed as if they hadn't put much thought and tended to rush, causing its plot to seem like some rehash of sorts rather than an entirely different game.

I do understand that Black 2 and White 2 are meant to be connected to its prequels--Black and White, which, in my opinion, were actually marvelous--but I don't necessarily believe it was a good idea for them to make them this close. Had they been a little more far, I'm sure it would have been a lot better in general. If they create any other main-series Pokémon sequel at some point in future, I hope they take this into consideration, if they're able.

Black. The choice of Pokemon at the start is absolutely abysmal - I was literally using just my starter until I beat the first Gym, because the choices were so poor and you couldn't trade until after the first badge - and the random encounter rate was horrendously broken. You could run around for several minutes at a time and not find anything, then not be able to take a step without being thrown into a battle. It made training very difficult, and very tedious.

After hearing so much about how the plot was different from the standard Pokemon games, I was quite disappointed to discover that this wasn't the case, and...I dunno, maybe it's because it started off so poorly, but Unova didn't really leave a very good impression on me. Black 2 more than fixed that by offering a more interesting plot and by changing things up a bit - and fixing the awful encounter rate and offering some variety in what was on the earlier routes - but I very nearly didn't buy Black 2 because of the mediocre time I had with Black.

Gonna have to go with GSC still, i'm sorry but things just don't feel very convenient there. Training sucks, most opponents are easy, and the new Pokémon are questionable for that time. I would mostly just rather play HGSS, but even if those didn't exist, I still would have a hard time going back to this. I want to stress that I don't hate GSC - I would just rather play any other main series game than it.

And I think i'll get even more hate for this, but RSE are still probably my second least favorites, mostly because of how annoying training is. Still as excited as ever for ORAS though, as i'm sure it will fix most of my big concerns now with those.

Since I haven't played every single Pokemon game, I'll probably just answer what I played.

My least fave is probably the games that feature Kanto and Johto, mainly because those two regions account for the smallest amount of all-time fave Pokemon for me, and they took longer to grow on me than later generations.

HeartGold & SoulSilver were great, but it's the lack of good training spots and the fact everything is so low-leveled and the fact I found it hard to build a team due to my general views on Kanto/Johto Pokemon being "boring and don't turn me on" so I didn't enjoy using them as much as most other games.

Second place would have to be Ruby/Sapphire/Emerald. Again, it's the lack of good training spots that comes into play here but hopefully Omega Ruby & Alpha Sapphire will fix all those issues now that the Exp. Share makes leveling up easier. Diamond & Pearl come in close due to the extremely slow gameplay, but at least Platinum was Sinnoh's saving grace.

Black and White, without a doubt. These games do have their plus points, but why they are my least favorites:

1. Rival battles. This is the only game when I can actually get sick of rival fights. It's almost at every city. Really irritating to say the least. XY had 3 "rivals" but only one is active while the other two only battle you towards the end.

2. Region + storyline issue. I really hated the fact that you had to go through 2 mountains one after another. Chargestone was terribly annoying and Twist Mountain was a chore.

3. Linearity: for some reason, Black and White seem to be really really rigid. Thankfully their sequels weren't as bad.

4. Massive level jump after E4. I was really shocked to see trainers at Lv65 immediately after the main storyline, and they were more pesky than tough.

5. Rather disappointing post game. Only the North East. Diving spots were absolute junk... Though it's not the worst.

Second least favorite is probably XY. Kalos is a beautiful region, but the games are just lacking. Really lacking. I wanted to tie it with Red and Blue, but I am more lenient with these two titles because they were the very first games and ran on obsolete technology by today's standards.

Tie between D/P and X/Y.
D/P is so goddamn slow it's not even funny, the Pokédex variety is awful, not much to do after E4, etc.

X/Y is easy as. It looks nice, though. It also has the problem of a terrible postgame.

I'd have to say D/P was my least favourites of any Pokémon game. As commented on by Gigadweeb above, it was just incredibly slow in it's gameplay. It felt sluggish and really unpolished to me. I was never a particular fan of their new Pokémon either and it took a long time to grow on me. Especially the extra evolutions for a few of the previous gen Pokémon like Rhyperior and Tangrowth (I did love Dusknoir though). God, I still think Rhyperior looks ugly.

I've always had a bit of a complex about Ruby and Sapphire. It probably has as much to do with my age at the time they came out and the fact that Pokemania had come and gone and the franchise was considered rather uncool among people my age at the time, but that game just really disappointed and frustrated me at the time.

Looking back I can see that there is a pretty clear vision Gamefreak had for the games and from a cohesive narrative point of view, the Hoenn games are among the best, but those aren't the sort of things I look for in a Pokemon game. I like to write my own story so to speak, so to me I want a Pokemon game to provide a great backdrop for my story, and that's where the Hoenn games really fell off a cliff for me as the backdrop is the same everywhere you go. It's just flat pastel colours, cheery upbeat music (with an overuse of Trumpet) and water, water, everywhere.

To me Ruby and Sapphire are like a free trip to Disney World but you can only go on the It's a Small World boat ride and you have to do it over and over and over and over again. It's cool at first but it quickly becomes torturous.

Probably the Sinnoh games. I'm not even sure why I dislike them, honestly? The cities are very nice and for the most part I liked all the Pokemon. But something about it ... I just didn't like it that much. : / And I guess I wasn't very fond of the rival in that game, either.

Black and white 2 black and white was fun bw2 I just didn't like it.

As of right now, D/P. I just could not get into them for the life of me. :( Sinnoh is a beautiful region, but I'm not really a person that likes cold weather and since a lot of Sinnoh is like that, that may be one of the reasons. Plus, I wasn't really a fan of the characters. None of them stood out to me.

Black and White

Such a disappointing region for me. To start I found a lot of the Pokemon designs to be really silly or just careless. They're some great Pokemon that have come out of that region and ones I really love, but I can't ignore how many poorly designed ones there are.

A lot of the characters were unmemorable or just very irritating. I found the rivals and team Plasma to be the most annoying characters to deal with. Really none of the gym leaders stood out to me. Also the champion was extremely disappointing. Only characters that shed any light were the E4 for being very unique.

I also have to agree with some of the points someone mentioned before me. There is a huge lack of variety of Pokemon in the beginning of the game that spans for a few towns I believe. It's really frustrating and it had me just sticking with my starter for a while.

These games were really made out to be a fresh start from games before. It seemed to be really emphasized that they were going to be a lot different. I even remember reading some reviews about how refreshing they were... but that didn't seem to be the case at all. It was the same exact thing with a few tweaks.

Besides all of that I just found the plot to be so terribly cheesy. It's like they tried to be "dark" but in the lightest way possible so it came out really lame.

This was the first time I decided to only buy one version because of how much I didn't enjoy it. I then ended up buying B2 about a month before X and Y came out because I was just dying for something new and it was only 20 dollars. A little better, but ehhh

The Unova games for me were probably my least favourite, I think mainly due to the region itself (I can't really put my finger on what was wrong with it but when I mentally picture any of the other regions, I know I preferred them a lot more); the Pokémon that were introduced were probably my least favourite of any gen; I didn't really like the way the moving battle sprites looked and I think I would've preferred if they'd stuck with having Contests (although I admire that they were trying something different). There are still a lot of aspects of Gen 5 that I like but unfortunately they're still my least favourite games.