Beat the 8th Gym leader.
the ground gym
stoopolis city
Beat the gym leader
The eighth badge can be obtained by defeating the gym leader in viridian city.
Beacon Badge
Sootopolis City. It is accessible only by using dive. The eighth badge can be obtained after the scenes with Rayquaza. The ice puzzle is fun, by the way.
The 8th Badge in Pokemon Diamond is called The Beacon Badge.
earn it.
I get my 8th badge in Sootopolis gym.
It depends which ones are you looking for. The 8th Badge is in Sootopolis, The 7th badge is in Mossdeep, The 6th Badge is in Fortree, The 5th badge Is your dad in emerald it is found at Petalburg, the 4th Badge is in Fallabore, The 3rd badge is in Mauville, The 2nd badge is in Dewford, The 1st badge is in Rustboro.
You have to beat the eighth gym leader to get to the Elite Four. Without defeating the eighth gym, you cannot get the S.S. Aqua ticket. You also cannot capture Lugia without the eighth badge.
== == You get the 8th gym badge in Sunyshore City. Hope this helps