HM05 (Flash/Defog)

Kanto (Flash)
Route 2 eastern side, Obtained from one of Professor Oak's aides in the gate as a reward for registering 10 Pokémon in the Pokédex (requires Cut). Requires the Boulder Badge to be used out of battle.

Hoenn (Flash)
Granite Cave from a Hiker near the entrance. Requires the Knuckle Badge to be used out of battle.

Sinnoh (Defog)
Solaceon Ruins, inside the lowest chamber.

Unova (Waterfall)
Route 18 at the south end of the grass across from the stairs leading west from the shack.