The 7th leader is Candice in Snowpoint City
The first gym in Pokemon diamond is in Oreburgh City
The 6th gym leader is in Canalave City.
just beat the fourth gym leader
It is Candace, The Ice-Type Gym Leader.
Pastoria City
orebourgh city
eterna city
hearthome city leader
in vilstone city not hearthome that's the fifth gym leader
the FIFTH gym leader is in HEARTHROME CITY! Hope that helps!!
Maylene isn't a gym leader. lol. actually,maylen is! she is in veilstone city.
You can only battle Hearthome City's gym leader Fantina after you have defeated Pastoria City's gym leader, Crasher Wake.