Empty Chamber glitch

The Empty Chamber glitch refers to a glitch in Super Smash Bros. Melee done using 's PK Thunder. This glitch is not practical or desirable for use in a traditional match, but may occur by accident. Performing this glitch correctly will cause Ness' next PK Thunder attempt to fail and spawn no projectile. The discovery of the glitch was a collaborative effort between, moose, and PKFreeZZy.

How to perform
Ness must perform his up special move while airborne then land, or while grounded then become airborne, while he is still controlling it. In this state, the Ness must then enter a damage state (e.g. suffer knockback or get grabbed) and have his PK Thunder reflected at the same time. If performed correctly, Ness' next attempt at creating a PK Thunder projectile will fail.

Explanation
When Ness becomes grounded after initiating PK Thunder in midair, or becomes airborne after initiating it while grounded, the set of functions that should run when he takes damage is cleared and not reset. Because of this oversight, if he takes damage while performing PK Thunder, his reference to the projectile is not cleared and the game believes he still has control over it.

Following this, if PK Thunder gets reflected on the same frame, instead of despawning because Ness is no longer in any of the PK Thunder action states, it remains active. In this series of events, the game misses another check to remove Ness' reference to the projectile because he is no longer its current owner.

In order for PK Thunder to be created, Ness's reference to the PK Thunder entity must be zero when reaching the final frame of his Up Special startup lag. However, by performing the aforementioned actions, the program now believes Ness still has an active PK Thunder projectile, and the condition to create a new instance fails.

Finally, Ness enters the looping state of PK Thunder where he would normally be able to control it. After failing another ownership check and returning zero, he immediately transitions to the ending animation of PK Thunder.

The glitch lasts for one use and PK Thunder returns to normal after this.

Demonstrations

 * A video of the Empty Chamber glitch during a match.