in the old game pokemon blue where can u find the FLASH move?

Answer 1

after you have a pokedex of 10, you can go back to the small by-way house that is the exit of viridian forest. either in here, or in the next building, there is an aide to professor oak that will give you the HM Flash

either way, it's in a building south of pewter city, and north of viridian city

Answer 2

lol nice dude ummmm u don't find it u get it from a gym leader