As visable items:
Route 214
Route 218
Route 224
Route 225
Route 230
Wayward Cave
Solaceon Ruins
Mt. Coronet
Victory Road
Stark Mountain
Using the dowsing machine:
Route 207
Route 210 (1st Part)
Great Marsh
Route 212
Snowpoint City
Galactic Veilstone Building
Victory Road (1st Part)
Victory Road (2nd Part)
Route 224
Route 225
Route 226
Route 228
If I have missed some just comment and tell me. But I think thats all.