I think you steal your friend's flag, but I'm not sure. I just got the game about two weeks ago, and I'm no expert, but since to go to Hearthome City there are boulders, and after stealing your friend's flag, you can move boulders. Just Guessing!
How many badges do you have?
Follow this path:
Twinleaf Town
Route 201
Sandgem Town
Route 202
Jubilife City
Route 203
Oreburgh City (Get 1st badge)
Route 203
Jubilife City
Route 204
Floroma Town
Route 205
Valley Windworks
Route 205
Floroma Town
Floroma Meadow
Floroma Town
Route 205
Valley Windworks
Route 205
Eterna Forest
Route 205
Eterna City (Get 2nd badge)
Route 206 (After receiving Bicycle)
Route 207
Mt Coronet
Route 208
Just head east on Route 208 and there you are, Hearthome City!
Now that wasn't so hard, wasn't it?
You can only challenge the Hearthrome City gym after you defeat the Pastoria and Veilstone City Gyms because the Heatherome City gym is to powerful.
Ill also give you the Hearthrome gym Pokemon
Drifblim Lv.32
Gengar Lv.34
Mismagius Lv.36
Enjoy:)
you have to go to veilstone city and go to the rocks and go through the building get past the guys and your done
he's in the light house
talk with him
defeat Cyrus and catch or defeat giratina
You have to beat Fantina first.
It is in Sunyshore City.
Volkner is located in Sunyshore City.
victory road north of sunyshore city but you have to have the sunyshore gym badge to get there
Well, you can't get to the Elite four without going to SunyShore, but you MUST either capture or KO Giratina before you're allowed to go to Sunyshore.
There are a lot of Beaches in Pokemon Platinum, There are two near the Lake Valor Resort, one in Sunyshore City, and more. Can you be more Specific, please?
It is in Sunyshore City.
the route on your way to sunyshore city
in sunyshore city
You can get seals from the Sunyshore City market.
Volkner is located in Sunyshore City.
victory road north of sunyshore city but you have to have the sunyshore gym badge to get there
you must talk to him in the lighthouse, in sunyshore then you can go in
The sailors near Sunyshore City.
North of Sunyshore City. It leads you to the Pokemon League.
to get to sunyshore city you need to go to the spear pillar hope I helped
in Pastoria City, Sunyshore City,Pokemon league,routes 213,222,223,224,230.
To get HM7 (Waterfall) in Platinum you can get it at Sunyshore City talking to Jasmine at the north of the city.