Foul Play uses the opponent's Attack stat (against them). Your Attack stat is irrelevant, though I have read that if the Foul Play user is burned, the damage will be halved - however the target can be burned and Foul Play will be unaffected.If I use Foul Play, is the damage calculated by comparing the two Pokemon's attack stats or just how high the opposing Pokemon's attack stat regardless of the move user's attack stat?
If anyone has any corrections, or I am just plain wrong, then let me know.