When performed, Paula and Poo use PK Teleport to appear beside Ness as he yells "PK Starstorm!" and they use their PSI powers to summon a barrage of meteors that rain from the sky. These meteors fall quickly in a narrow stream downward, the direction of which can be angled left or right using the directional inputs. Each meteor deals 20% flamedamage and strong knockback to opponents hit, making them useful for both racking up damage on and KO'ing opponents. After a certain period of time, the meteors will stop falling and Paula and Poo will leave using PK Teleport, ending the move.
PK Starstorm (localized as PSI Starstorm in EarthBound) is a PSI attack in the EarthBound series that first appeared in EarthBound and later appeared in Mother 3. In both games, it is a powerful attack in which the user uses psychic power to send down stars on all enemies. The move is impossible for any target to dodge, but it can be reflected by sufficient PSI shields.
However, the move is not learned by Ness in EarthBound, instead being learned by his companion Poo. This is referenced in the Final Smash by having Poo appear alongside Ness to use the move.