If you mean by "flash light" the old term for a hand-torch, it will, but it's not recommended for caving use.
If you mena photographic flash, then yes it will, but cave-Photography is quite specialised, needing a lot of skill to obtain really good results. It can be very rewarding though, as you have to supply all the light necessary so potentially have considerable control over the effects. You also usually need to be a competent caver, too!
get the item flash
You can't make a cave disapear. You can light up caves with flash, and that's about it.
If by Underground Caves you mean caves where you just have a small radius of light around you, then you talk to the Hiker in Dewford Town caves and get HM Flash from him. Beat the Dewford Town Gym Leader and teach Flash to a suitable Pokemon. When in these caves press the START button and activate your Pokemon team and right click the Pokemon you taught Flash to and activate Flash on the List 1. Talk to Dewford Town Caves Hiker 2. Beat Dewford Town Gym Leader 3. Teach Flash to Pokemon 4. Use in Dark Caves. Viola!
Use the HM Flash this is given by the sage at the top of sprout tower.
in caves and duengeons
use flash
Teach it to a Pokemon, then select the Pokemon you taught it to in the party and select Flash.
Two reasons: it disturbs the cave's inhabitants, bats, and people's eyes adjust to the low light conditions and flashes can damage people's sight. Direct flash photography in caves usually leads to poor picture quality, anyway. The best way to use a flash in a cave if you are going to is to point it another direction than straight forward.
By using the TM Flash
Teach a move to a Pokemon that can learn it via HM and then, after defeating Falkner in Violet City, select that Pokemon in your party and select Flash to light up dark caves, such as Dark Tunnel.
Flash Film Works was created in 1993.
The population of Flash Film Works is 50.