You cannot get Flash Cannon in Sapphire, it was a new move made for Diamond, Pearl and above. It wasn't made when Sapphire, Ruby, Emerald, Leaf Green or Fire Red came out.
No.
No, Zubat cannot learn Flash.
You obtain Flash Cannon after defeating the 7th Gym Leader, Byron in Canalave City.
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The following Pokemon that you can easily get to learn Flash in Sapphire: Beautifly or Dustox Lotad or Lombre Oddish Gloom
You cannot. Flash Cannon was not introduced until Generation IV, and Fire Red is a Generation III game...and a Generation I game.
Find an Abra to give flash in the cave in dewford.
krabby
Somewhere in Twist Mountain
It learns it at level 80
You can't its not a move in emerald.
Many like Bastiodon.