HM08 (Rock Climb/Dive)

Kanto
HM08 does not exist in the Kanto region.

Hoenn (Dive)
Mossdeep City, from Steven in his house after defeating Team Magma. Requires the Mind Badge to be used out of battle.

Sinnoh (Rock Climb)
Route 217, northeast of the Hiker's house. Requires the Icicle Badge to be used out of battle.

Unova
HM08 does not exist in the Unova region.