Tulunk Village

My favorite pokemon game must be crystal because I really enjoyed playing through it , the animations are really cool and Suicune is my favorite pokemon. I can say that Sapphire must be my second fav as kyogre kicks a** and it was the first official pokemon game I played.(first was a bootleg emerald that deleted your save file after you managed to beat the elite 4.)
How about you guys ,which pokemon game captured your hearts?

Crystal

I've gotta say Crystal too, it introduced a lot of good changes and it's the game I probably spent the most time playing...XD I was sad when they didn't include the girl from Crystal in HGSS. *sigh*
G/S/C was great for making so many improvements from R/B/Y, plus Johto was a pretty cool region. XD Ruby/Sapphire seemed like such a step back features-wise (since they got rid of the PokeGear), so even though I like the games now, it took me a long time to start giving them a chance. :/

B/W is probably a contender for my favourite gen now though, because it's awesome, and they managed to make Unova much more interesting than Hoenn or Sinnoh IMO. The new Pokemon are all pretty great too.

I love all of the Pokemon games, but I think the most nostalgic for me has to be Pokemon Gold and the original Red/Blue games, particularly Gold with Ho-oh and Cyndaquil. I'm also fond of the Mystery Dungeon games, even though they're spinoffs from the main series. They have very good stories and I enjoyed the gameplay.

Nostalgia-wise, I would say Gold is my favorite because I remember the first time I played it, watching the intro and thinking "OMG EVERYTHING IS SO NEW AND COOL...!" While I enjoyed the 3rd and 4th gens, neither really recaptured that feeling. I liked the gameplay improvements and new Pokémon, but there wasn't that something. I think that White, however, did a really good job of rekindling some of that! The fact that I REALLY LOVED almost every single new design helped a lot, I think. (omg the spiders alone might make 5th gen = best gen)

If it matters, the main series games I have owned are as follows (in order):
Blue, Red, Yellow, Gold, Ruby, Emerald, LeafGreen, Diamond, HeartGold, White

mine would be a tie between gold and sapphire. the two i played the most when i was younger

By god I long to play red and blue again.

I actually really liked Colosseum even though it was very short and seemed kind of unpolished. It was just nice to see a bit of deviation from the typical Pokemon formula. It was pretty awesome starting off as a bad*** ex-criminal blowing up a factory, and starting with two pokemon at decent levels so I didn't have to go through all the boring early stages of Pokemon. it just puts you right into the action. I liked the whole shadow pokemon thing and how the game actually revolved around the plot, and the music was pretty awesome too. I was really disappointed that Battle Revolution didn't have an RPG mode, so I REALLY hope that there'll be one on the Wii U

Red Yellow Blue Gold Silver Crystal

Owned them all at one time or another. Then the GB color went bust - too many droppings, the cart battery gave out, so switched to emulator and roms