You can get it in Challenger's cave
No. Scizor can't use the stone edge move in Pokemon.
TM71 - Stone Edge - Victory Road 2F
You can buy stone edge at the battle frontier TM stand.
Stone edge is a move that was invented in diamond and pearl and platinum you cannot have any Pokemon learn 4th generation moves like stone edge in firered because they don't exist. But you can migrate a aerodactyl to diamond or pearl or platinum and have it learn stone edge there.
black stone
in pokemon black and white
minccino
the light stone isn't in Pokemon white only the dark stone in white and the light stone in black
Try Corsola or Kabutops.
Victory road B1f
You can only find a Magma Stone in Pokemon Black 2, White 2, Pokemon Diamond, Pearl, and Platinum. It is not available in Pokemon Black and White.
Pansear uses a fire stone to evolve into Simisear.