The Lustrous Orb is an exclusive item for Palkia, introduced in Generation IV.
The Lustrous Orb takes on the appearance of a large pearl in a glossy blue colour.
If held by Palkia, it boosts the power of Dragon- and Water-type moves for 20%.
In Platinum, it is required to summon Palkia at Spear Pillar.
Lustrous Orb in the anime