HM05

HMs are multiple use TMs that serve a purpose out of battle, as well as being moves for in-battle use; however, in order to use an HM's purpose out of battle, a Gym Badge is required. HM05 is:

Gen	Move	Locations		Badge
I	Flash	Route 2		Boulder Badge
II	Flash	Sprout Tower		Zephyr Badge
III	Flash	RSE	Granite Cave	Knuckle Badge
		FRLG	Route 2	Boulder Badge
IV	Defog	DP	Great Marsh	Fen Badge
		Pt	Solaceon Ruins	Relic Badge
	Whirlpool	HGSS	Rocket Hideout	Glacier Badge

Trivia

• Up until Pokémon HeartGold and SoulSilver, this was the only multiple-generation HM that is not truly required to move on.
• In Diamond, Pearl, and Platinum, HM05 has the item sprite of a Water-type HM, even though Defog is a Flying-type move. It is possible that this is because Defog's HeartGold and SoulSilver counterpart, Whirlpool, is a Water-type move.
• HM05 is the only HM and only machine move so far that has changed moves within a generation, from Defog in Diamond, Pearl, and Platinum to Whirlpool in HeartGold and SoulSilver.