One-hit KO

The most notable one-hit KO: a smash attack with the Home-Run Bat.

A one-hit KO (abbreviated OHKO), also known as hit KO or hit kill is an attack in Super Smash Flash 2 which, as the name suggests, KO's opponents in one hit when their damage 0% and if the victim's flight path is not obstructed. As such, they are very powerful moves and most have to be charged. Self-destructs do not count as OHKOs. In order to acknowledge the attack was a OHKO, it has to share the following restrictions:

In Super Smash Flash, there are no OHKO attacks, as hitboxes have a constant, per-frame damage output rather than a single set value. However, instant-KO attacks are commonly erroneously referred to as OHKOs regardless.