The 8th Gym Leader has electric type pokemon. Your best bet to defeat him is Ground or Rock pokemon. Electric types are not effective against ground types.
Defeat the eighth gym leader.
volkner
beat the #?*@! gym leader
By beating the gym leader
The eighth gym leader is there so you will have to defeat all the others first.
you need to defeat pastoria city's gym leader
a gym leader can't teach a Pokemon that move but you have to defeat the 6 gym leader in order to teach that move
USE A FIAH TYPE.
To get the 8th Gym Leader to return to his Gym in Viridian City, you must defeat all 7 other Gym Leaders.
sure is
In sunyshore city
the 8th leader in platinum uses electric type so i would recommend using ground type Pokemon..............if you don't have ground type Pokemon don't worry he isn't that good