A Blue Scarf is an item introduced in Generation III that raises the power of Beauty moves in Pokémon Contests in the Hoenn region games and the Sinnoh region games.
A Blue Scarf can be found by the Chairman of Slateport City if the player shows him a Pokémon with high Beauty stats. In the Sinnoh region games, this item can be found by the Scarf Guy in Pastoria City if the player, like in Generation III, shows him a Pokémon with high Beauty stats.