The Miror Radar allows the player to track down Miror B.'s location in case they've failed to snag a Shadow Pokémon in order to battle him and get another chance at snagging it. When the Radar's alarm goes off, the player can check it for Miror B.'s current location. If the location is not visited within a certain amount of time, the Radar's signal will be lost and the player has to wait for a new alert.
Miror B. can appear at Pyrite Colosseum, Realgam Colosseum, or one of the three Poké Spots. If found at a Colosseum, he will randomly replace one of the Trainers from the current round. The Radar will also alert the player of Miror B.'s presence at the Outskirt Stand when the player first visits the location, and at Gateon Port when the player first enters it after having snagged 82 of the 83 Shadow Pokémon.
If the Radar indicates that Miror B. is at one of the three Poké Spots, there's a chance that Miror B. himself won't be at the location, with only Trudly and Folly appearing there instead.
The Radar won't go off while the player's Snag Machine is stolen, excluding the predetermined alert at the Outskirt Stand.