The fifth gym is in hearthome city, if you cant get in you have to speak to the gym leader at the contest hall there. (good luck)
the fith gym is a sychic gym its in heathrome city
petalburg
In the concert hall to the left
you can get the fith badge by going to petalburg the poke gym there.
The first gym in Pokemon diamond is in Oreburgh City
the fifth gym on Pokemon diamond is the one in herthome city,
the fith gym leader in crystal is on an Island in the southwest of Johto. use surf to get to him
The seventh gym in Pokemon Diamond, Pearl, and Platinum is located in Snowpoint City, which is to the East of Lake Acuity.
The Pokémon the second Gym Leader has in "Diamond" are Cherubi, Turtwig and Roserade.
hearthome gym. you know where that is.
you beat the gym leader
the sixth gym is in canalave city