i mean there isn't any sun light....
It can be used anyway. The game isn't fully based upon the Earth, and besides...that would be a bit stupid... BTW this still applies for Sunny Day too, Solar Beam is a one turn move if sunny day is active.
http://bulbapedia.bulbagarden.net/wiki/SolarBeam_(move)
Yes.I have used solarbeam before in a cave before.If you use sunny day though it will be a one turn move.
