PK Starstorm
PK Starstorm is the Final Smash of both Lucas and Ness in Super Smash Bros. Brawl. The character summons a rain of actual stars from the sky (or astronomically seen, meteorites) while yelling "PK... Starstorm!!", which strike the stage. Lucas' PK Starstorm is more effective on smaller stages and Ness' PK Starstorm is more effective in larger stages. The move differs slightly for the two characters who use it; Lucas' meteors rain downwards and slightly inwards, dealing 14% damage, whereas Ness' meteors spread out in a fan-like shape, dealing 20% damage. Ness' PK Starstorm knocks the opponent up while Lucas' knocks the opponent to the side. Lucas's PK Starstorm has meteors swarming in groups, whereas Ness' PK Starstorm comes down individually.
Ness Trophy
Ness as he calls down a host of damage-dealing stars in his Final Smash. Everyone on the screen must dodge like crazy to avoid getting hurt, but that's no easy task. This attack appeared in the Mother series, but it was Poo, not Ness, who wielded it. Perhaps Poo taught Ness the secret of the attack for use in Super Smash Bros. Brawl.
Lucas Trophy
Lucas' Final Smash. He pulls a large group of stars from the sky and sends them smashing down among his enemies, causing damage to one and all. In Mother 3, this move was used by Lucas' traveling companion, Princess Kumatora. As Ness learned this move from Poo, Princess Kumatora taught Lucas when he learned he would appear in Super Smash Bros. Brawl.
Origin
PSI Starstorm (PK Starstorm) first appeared in EarthBound. PSI Starstorm is a very powerful attack that is impossible for enemies to avoid. The move is never taught to Ness, but it is taught to Poo by the Star Master. There are also two different levels of the move: PSI Starstorm α, and PSI Starstorm Ω. The amount of damage that PSI Starstorm can vary from 270 damage, to 900 damage. PSI Starstorm later appeared in Mother 3. It acts the same way as it did in EarthBound, except there is now only one level of it, and can deal 650 damage, to 680 damage. In Mother 3, Lucas also never learns PSI Starstorm, but is instead taught to Kumatora by Ionia. In Brawl, Ness and Lucas use PSI Starstorm as their Final Smashes. While the Final Smash covers the majority of the stage, it is possible to dodge it. It is stated in both of their Final Smash trophies that their friends taught them this move to be used in Brawl.
