BrightPowder is a Held Item that gives a 10% increase to the Evasion Statistic of the Pokémon that is holding this item.
Trade an Articuno, Zapdos, Moltres or Mewtwo from one of the Generation I games Red, Blue, or Yellow. Each of these Pokémon will be holding a BrightPowder.
In both of these generations, BrightPowder is available at the Battle Frontier, which is limited to the Battle Tower in Ruby and Sapphire. There is also a Battle Park in Diamond, Pearl and Platinum in which BrightPowder can also be obtained.
In Heart Gold and Soul Silver, a BrightPowder can be found within the Radio Tower in Goldenrod City.
A BrightPowder can be found within Chargestone Cave, and can sometimes be obtained at Gear Station.