PK Fire
PK Fire is Ness's side-b.
You can activate it on any hurtbox, not just opponents directly. This includes shiek needles that have scattered, link/ylink arrows or bombs, fly guys.
Edge Cancel PK Fire (ECPKF)
Usually PK Fire has 30 frames of landing lag from the aerial version, but using momentum from a DJC PK fire to land on either the edge of a platform or a stage you can cancel it by sliding off or teetering.
The most consistent way to set it up is wavedashing off a platform then double jumping forward and then using PK Fire. This works on every stage with platforms besides battlefield.
Though you still are able to jump up from the stage and then DJC PK Fire. It's just inconsistent.
Doing ECPKFs at the edge of the stage and not off a platform are incredibly risky and almost never worth the reward if you hit it and if you overshoot it you are most likely not going to make it back to the stage.
Difference between forwards & backwards DJC PK Fire
Turns out that Ness's momentum when DJC depends on the type of DJ used. First off there's three types of double jumps Ness has, those being, forwards, backwards, and neutral DJ. These all have very slight differences when DJCed with. Forwards has the most momentum when DJC. Backwards has less momentum when DJCed making it possible to do turn around DJC backwards ECPKF at round start consistently. Finally, there's the neutral DJC ECPKF... It's useless. If you misinput this expect to get punished.