Change your preferences here.
Deals damage. If the move would cause enough damage to the opponent to faint it will always leave the opponent with 1 HP instead, regardless of how much damage would have been inflicted.
False Swipe has no competitive use in singles. In doubles and triples it can be used to reduce a teammate to 1 HP safely in order to bring the Base Power of Flail or Reversal to 200.
Return is a much stronger alternative with no drawbacks.
Double-Edge is an even stronger alternative that inflicts recoil on the user.