The is a huge white rock, with dive spots round it, dive there, and you find an underwater cave. Go in and surface again and You find Sootopolis
Use Dive.
Sootopalis City
use dive in the dark water then go into a cave. ue dive again and you should be in sootapolis city
Ever Grande City
you can get one in petalburg city
Staleport City and LilyCove City
Lilycove City.
the third badge in sapphire is at mauville city(north of slateport city)
Fortree City.
Peatlburg city
in evergrande city.
The Move Deleter in Pokemon Ruby, Sapphire, and Emerald is found in Lilycove City.