Sheen (Japanese: けづや fur sheen) is a property of a Pokémon in the Generation III and IV core series games. It affects the score a Pokémon receives in the primary judging of a Pokémon Contest or the Visual Competition in a Pokémon Super Contest.
Sheen was not named in-game until Generation IV, although its Japanese name is present in debug text in Pokémon Ruby and Sapphire.
All Pokémon initially have sheen of 0, except Pokémon received in in-game trades in the handheld Generation III games, which begin with a sheen of 10.
When a Pokémon eats a Pokéblock or Poffin, that food item's feel or smoothness is added to the Pokémon's sheen, up to a maximum of 255. In Pokémon HeartGold and SoulSilver, having the haircut brothers or Daisy Oak groom a Pokémon also increases its sheen. If a Pokémon's sheen would exceed 255, it becomes 255 instead (the Pokémon's condition is still increased as normal).
A Pokémon with 255 sheen cannot eat any more Pokéblocks or Poffins in the Generation III and IV games. Sheen is permanent and cannot be decreased or reset. Therefore, a Pokémon can be fed more Pokéblocks or Poffins that have low smoothness.
Although the sheen value remains in the internal Pokémon data structures from Generation V onward, it has no effect. In Pokémon Omega Ruby and Alpha Sapphire, Pokéblocks neither affect nor are affected by sheen.
Sheen is displayed on the same screen as a Pokémon's condition, located in the PokéNav in Pokémon Ruby, Sapphire, and Emerald and the Pokémon's summary screen in Pokémon Diamond, Pearl, and Platinum, as a series of sparkles.