After beating the eighth gym leader Clair in Pokemon SoulSilver, the player must first enter the shrine of the Dragon's Den to obtain the Dragon's Fang and pass the test of the Master of the Dragon Clan. Unlike the previous gym leaders, Claire will initially refuse to admit defeat and the player can only earn the eighth and final badge after completing the quest for Claire.
The following shows how to complete the quest after beating the eighth gym leader in Pokemon SoulSilver.
Step 1: Cross the Whirlpool
Proceed to the back of the gym to the dock and surf to the left of the dock. The player must get to the giant whirlpool and then cross the whirlpool.
Step 2: Retrieve the Dragon Fang
Surf to the shore on the lower right corner and retrieve the Dragon Fang on a ledge to the north.
Step 3: Pass the Dragon Master Test
Surf to the shrine and pass the test of the Dragon Master.