Pokémon Colosseum/Realgam Tower

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The actual Tower, is way in the back. To get there you must go through the Rail Network. The door to the Tower is locked hard, and to open it you need 4 Keys, which are retrieved by the defeated bosses.

As you enter the first Dome, take the door to the right. There, is the Miror B.

For defeating him, you will receive the Red ID Badge, 1 of 4 badges needed to enter the main Tower. Head to the main Dome and head up. This Dome has a PC and Health Restoring machine. To use them, you have to fight the Peon.