By using the HM Surf
cancalave city
Petalburg City is not in Pokemon Platinum.
You can find a Shell Bell at Hearthome City in Pokemon Platinum.
below hearthome city
Hearthome city.
In Pokemon Platinum, Diamond, and Pearl, the department store is is Veilstone city.
Eterna City
hearthome city
pancakes
In Shunishoart City.
you surf
Jubilife city