Since X and Y have been out for an appreciable period of time now, and since I assume (hope) that the new game shine has worn off, I believe it is time to rank all the Pokemon games now in the premier handheld gaming franchise.
Here's my ranking (I am including the remakes, but not the original games):
1. Pokemon HeartGold/SoulSilver
Had the best regions, the best atmosphere, the best Pokedex which made it possible to obtain almost every single Pokemon in game legitimately, a fun plot line that expanded on the original, a staggering amount of things to do, the best interface, the best soundtrack in the series and an incredible post game. Basically, Pokemon HeartGold and SoulSilver remain the pinnacle and the ultimate realization of the series yet.
2. Pokemon FireRed/LeafGreen
The most free form, open world Pokemon adventure yet; light on story, but it was your tale, your narrative. Memorable characters, great Pokemon selection, and a really nice post game, coupled with some of the best pacing in the series. The music was butchered from the originals, but on the whole, FireRed and LeafGreen took the simplest Pokemon design and made it even more focused.
3. Pokemon X/Y
The step to 3D was immaculate, and breathed new life into the series, making Kalos a beautiful region; the battles looked great, the music, especially in the second half, was masterful, the online functionality was probably the best seen yet in a handheld game, the concessions made to making competitive battling less arcane made it a much better game, the new Pokemon introduced were uniformly great, the Pokemon selection in game was second only to HeartGold/SoulSilver, the new type matchup chart reinvigorated the battles, and the trimming away of the fat was great. A lack of post game, along with a story that was a definite step down from Black/White, and a low number of new Pokemon are the low points of an otherwise incredible Pokemon game.
4. Pokemon Black/White
A proto Pokemon X/Y, the emphasis on presentation and storytelling was something fresh for the franchise. The experimentation was 3D breathed new life into a series that was otherwise stagnating, along with the more dynamic battle screens. The story was great and thought provoking, the music was expectedly awesome, and the fact that there were all new Pokemon was great. They trimmed away the fat, took the first steps towards X and Y's persistent online connectivity with the C-Gear, and even simplified overworld exploration by taking away the HMs. A very poor postgame, linear overworld, and some really poor Pokemon designs were its key worst points,
5. Pokemon Diamond/Pearl/Platinum
Sinnoh was massive, mysterious, and probably the best region in the series yet. The lore the games introduced to the series, along with the legendary Pokemon, were great. Diamond/Pearl/Platinum didn't introduce all that much to the series, choosing instead to refine on Ruby/Sapphire/Emerald, but they did offer an incredible, if traditional, Pokemon adventure, with a great soundtrack to accompany players, and an incredible atmosphere. They also introduced online to the series, and had a great post game. Poor selection of Pokemon in game, coupled with a really lame story, some pacing issues, and a game that ran excruciatingly slow, mar the overall experience though.
6. Pokemon Black 2/White 2
Black 2/White 2 had an incredible amount of content- the main game itself was a good fifty or so hours, but it was the incredible post game where the games shined, with the Pokemon World Tournament, especially, being the highlight. Great Pokemon selection and a great soundtrack make these worth the price of admission, although overall, the campaign is poorly paced, the story is almost comical after Black/White, and the games just suffered from a heavy case of franchise fatigue.
7. Pokemon Ruby/Sapphire/Emerald
Look, these were great games. They introduced to much to the series- EVs, IVs. Natures, Abilities, Hidden Bases, Weather, Pokemon Contests, Double Battles, and the new engine on which all future Pokemon games would be built. But they simply don't hold up to the rest of the series. The new Pokemon introduced were great, Hoenn was a great, exotic region, and these were the first Pokemon games to try and tell a story. The soundtrack was great too. But they broke compatibility with the previous games, stripped down some great features like day and night, featured a paltry post game, had a broken leveling curve, had the worst pacing issues in the series, and in general felt like a step down from Pokemon Gold and Silver. They were fun to play because they were Pokemon, but ultimately, they were the worst in the series.
So how would you rank the Pokemon games, and why?