These are sprites that are from the Pokemon platform/hand held games. Sprites for XD: Gale of Darkness/Colosseum has been moved to Other Sprites. Note that sprites can be used in more than one generation of games. A list of the games that the sprites are from is below.
Mystery Dungeon Red/Blue Rescue Team, Trozei, Pinball, Ruby/Sapphire and FireRed/LeafGreen, FireRed/LeafGreen, X/Y and Omega Ruby/Alpha Sapphire, HeartGold/SoulSilver, Mystery Dungeon Red/Blue Rescue Team, Conquest (Articuno Only), Red/Blue/Green and Yellow, Red (Ja)/Green, Red/Blue, Yellow, Gold/Silver and Crystal, Gold, Silver, Ruby/Sapphire/Emerald and FireRed/LeafGreen, Ruby/Sapphire, FireRed/LeafGreen, Diamond/Pearl/Platinum and HeartGold/SoulSilver, Diamond/Pearl/Platinum, HeartGold/SoulSilver, Black/White and Black 2/White 2, Black/White and Black 2/White 2, Ranger: Guardian Signs
I decided to list the sprites that are animated since the X and Y sprites are animated.
Sprites are in this order: Ruby/Sapphire and FireRed/LeafGreen, HeartGold/SoulSilver, Trozei, Pinball, Crystal, Emerald, Diamond/Pearl/Platinum, HeartGold/SoulSilver, Black/White, X/Y and Omega Ruby/Alpha Sapphire
The sprites in this section aren't from the original type of games. These sprites are included in Pokemon game sequels, like Pokemon Rumble World for example.
In this order; XD: Gale of Darkness/Colosseum, Rumble World, Shuffle, Pokedex Pro, and Conquest (Articuno Only)