you need to use water type Pokemon that are stong.
to get to the gym leader with few battles- use the stairs to the
left of the door!!
you have to switch them in the right position to walk on until you get to him
Have a strong fire type pokemon.
You have to defeat the last gym leader
Sunyshore city, where the last gym badge will be.
In Sunnyshore city same as pearl/diamond.
catch dialga the go to sunnyshore
The first gym in Pokemon diamond is in Oreburgh City
the fifth gym on Pokemon diamond is the one in herthome city,
The last gym is in Sunnyshore city and you need to go to the lighthouse go to the top floor and talk to the gym leader and he will go to his gym and you then can fight him. I hope this was helpful!
in the grass in the last city the 8th gym leader
After you do the second to last gym it becomes available
Go into her Gym and make it through the maze. She battles with Ghost Pokemon, watch out for the Mismagius.
Battle the guards and do'NT tell them i said that.
He is the first Gym Leader you meet and he is in Oreburg City, through the passage east of Jubilife.
use Pokemon diamond/peral/platinum's effect calculator and find out what the gym leaders weakness is