So every False Swipe related question I go to, the answers say it is not useful in competitive. But if it leaves your enemy with only 1 HP, won't just one more move kill the enemy, so that's only 2 moves to kill any Pokemon? I think that's the most op thing ever in competitive. Any reason why it isn't useful in competitive?
False Swipe doesn't automatically leave your opponent with 1 HP. This is what Bulbapedia says:
False Swipe inflicts damage, but will leave the target with 1 HP if it would otherwise cause it to faint. If the target has 1 HP remaining, False Swipe will hit and leave the target at 1 HP.
Source
It can never faint the opponent, and it's only good in-game for catching Pokemon, so it's a waste of a moveslot in competitive. It's also incredibly weak (40 base power) and doesn't affect Ghost types.
Hope I helped!