Instructions
Go to the Goldenrod tunnel on the left-hand side of town close to the game corner.
Walk down the stairs, and then take the first hallway to your right.
Walk to the end of the hallway after you encounter the girl in the Kimono. Open the door using the key you got from Petrel in the radio tower.
Defeat your rival in battle after he challenges you. Use fighting or fire-based attacks against his Sneasel, ground moves against Magnamite, ghost or psychic attacks against Haunter and electric against Golbat.
Defeat the other Team Rocket members.
Walk up to the colored switches in the center of the room. Press the blue, then the green and finally the red switch to clear a path to the bottom area.
Follow the path you have created with the switches until you reach a female enemy. Defeat her and exit through the door behind her.
Defeat all the enemies as you make your way through the room until you reach the director. The path to him is straightforward so you won't get lost.
Speak to the director to receive the card key that unlocks the door to the top of the tower.
Exit through the nearby door. You will find yourself in the basement area of the department store.
Return to the radio tower and go back up to the third floor where the locked door is located.
Unlock the door using the card key you received from the director. Continue up to the top of the tower for your showdown with the Team Rocket leader.