Asked over 4 years ago in Cheats & Codes
Games: Pokemon Pearl (DS)
You got to have 7 badges, and then he will let you in, to battle the 8th and final gym leader.
You have to get all the other 7 bagdes. After that, you will be able to move to Sunyshore city, where the 8th bagde is .
There is a way also that i found on the internet :
©Copyright 2002-2013 GameFly, Inc.