A fossil is an item that can be found in certain caves and dug up in the Underground. Fossils can then be resurrected into the Pokémon it is a fossil of. Each Generation has its own set of fossils consisting of at least two stage-two evolutionary families with Generation II being the exception.
In order to resurrect the fossil into a Pokémon, you'll need to visit a building, usually a museum.
- In Pokémon Red, Blue, Yellow, FireRed and LeafGreen, visit the Pokémon Lab on Cinnabar Island and enter the room on the far right.
- In Pokémon Ruby, Sapphire, and Emerald, visit the Devon Corporation in Rustboro City and have it resurrected by the scientist.
- In Pokémon Diamond, Pearl, and Platinum, visit the Oreburgh Museum in Oreburgh City.
- In Pokémon HeartGold and SoulSilver, visit the Pewter Museum in Pewter City.
- In Pokémon Black and White, visit the Nacrene Museum in Nacrene City.
- In Pokémon X and Y, visit the Fossil Lab in Ambrette Town.
- Generation I is the only Generation to have more than two fossils, Old Amber.
- Generation II is the only Generation without fossils.