How do we get hm05 flash?

To obtain HM05 (which contains the move Flash) in Pokémon games, you typically need to progress through the storyline until you reach a specific location, often a cave or a town where an NPC will give it to you. In some games, it may be found in a hidden location or as part of a quest. Be sure to check in-game guides for the exact location relevant to the specific Pokémon game you are playing.