The Diploma is an item awarded in all of the main handheld Pokémon games for completing various modes of the Pokédex. It is always obtained from Game Freak's lead developer, usually at their headquarters at Celadon Condominiums. In games where a Game Freak building is not visitable, he's on vacation at the top floor of Cove Lily Motel at Lilycove City (in Pokémon Ruby, Sapphire, and Emerald), or at the northwesternmost house of the Hotel Grand Lake at the Valor Lakefront (in Pokémon Diamond, Pearl, and Platinum), where he also gives out the diploma. The diploma is not an item in the regular sense as it is not added to the player's inventory; to view it after obtaining it, the player must talk to said lead developer again. In Pokémon Black and White, the diploma is instead sent to the player's bedroom for display.
In Generation I and II, there is only one diploma in the game, awarded for capturing most of the Pokémon revealed at the time. From Generation III onwards, there is one diploma awarded for completing the regional Pokédex and a second for completing the national one. Event legendary Pokémon (Mew, Celebi, Jirachi, Deoxys, Manaphy, Phione, Darkrai, Shaymin, Arceus, Victini, Keldeo, Meloetta and Genesect), as well as Ho-Oh and Lugia in the Generation III games and Pokémon Diamond, Pearl, and Platinum, are not required to qualify for any of the diplomas. In Pokémon Diamond, Pearl, and Platinum, one needs to only see all of the Pokémon in the Sinnoh Pokédex to qualify for the regional version of the diploma.
In Pokémon Red and Green, it was long rumored that the player could obtain Mew from Game Freak's lead developer in Celadon Condominiums after completing the Pokédex of 150 Pokémon. However, this is false; instead, a diploma is awarded for finishing the Pokédex.