As seen in Colosseum, the shadow Pokemon are back! In order to capture them from evil trainers, you must snag them with the snag machine on your arm. In order to tell if a Pokemon is a shadow Pokemon, you use the radar eye-piece, which straight away notifies you of the shadow Pokemon. These shadow Pokemon have Shadow Attacks, special shadow attacks only shadow Pokemon can learn. To trade the shadow Pokemon over to FireRed/LeafGreen/Ruby/Sapphire/Emerald, they must first be purified.