PK Flash

PK Flash is Ness's neutral-b. Generally way too laggy to be used seriously, but it can situationally work decently well as an edgeguard against some characters.

PK Flash Trap

PK Flash Trap is a bug involving PK Flash where when using Flash in the air and then landing on the ground (or vice versa, but that's less practical) will cause the projectile to detonate upon being hit instead of losing control and it being absorbed into the ground.

This is mainly able to be used against opponents that don't have any idea about the tech as it can be beaten by grabbing and using throw invincibility to avoid the Flash hitbox. It can also punish poor recoveries that don't sweetspot the ledge.

When being hit out of PK Trap at low %s you are able to attack the opponent while they are still in hit stun allowing for high damage combos.

However PK Trap (and PK Flash in general) is a very all or nothing trick that is very risky and can backfire if things don't go your way.