go to a man in purple in a cave.
The following Pokemon that you can easily get to learn Flash in Sapphire: Beautifly or Dustox Lotad or Lombre Oddish Gloom
Find an Abra to give flash in the cave in dewford.
there are many MANY Pokemon that can use the hm flash in Pokemon sapphire. the following Pokemon can: grovile( treeko),kirlia(ralts)shroomish, eletrike, Roselia, plusle, munun, magnemite, voltorb and many more
When a Pokemon has the move Flash, you go into Party, then select the Pokemon with Flash using the 'A' button and there should be an option that says "Flash". It is only usable in dark locations or within battle.
mostly phychic types like Abra
Of the seven pokemon available in Granite Cave, the cave northwest of Dewford Town, only Abra and Sableye can learn HM05 Flash.
try it on normal or your nonfavorite pokemon Try on a pikichu
Dewford town. Beat Brawly.
Upon entering the Dewford cave, there should be a hiker guy right by the entrance. Talk to him and he should share Flash with you.
Nincada is a fantastic Pokemon to use these moves on. Not only can it learn Flash and Rock Smash, but also Cut, Dig, and Secret Power which are all moves that are required later on.
in the granite cave you have to find steven and get flash when you get in the cave there is a man in a pink hat talk to him
Pokemon Ruby has Pokemon that Pokemon Sapphire does not and Pokemon Sapphire has Pokemon that Pokemon Ruby does not.