Negative Zone

The Negative Zone is Luigi's Final Smash. It has unique properties. Luigi dances, and a large, greenish-tint void surrounds him. Inside the void, the colors of the environment, the other characters inside the void, and Luigi himself become inverted. Opponents caught in the void fall victim to all sorts of afflictions given out randomly to opponents. Luigi dances and chants for the first few seconds of the Final Smash, but is unaffected by the Negative Zone (except a minor decrease in speed while still being faster than most other characters) when he's done. Even if Luigi dies, the Final Smash does not immediately end. Using this move while over the edge may result in an SD as the zone sinks until Luigi's dance is finished and while he is dancing he cannot move. If opponents are caught in the Negative Zone, they become open targets as Luigi charges his foes and knocks them off the stage. It also appears that the Fire Jump Punch can be used to great effect, very often dealing a one-hit KO in the affected zone. When the Negative Zone disappears, the flowers and the dizziness opponents were given will remain and inflict slightly more damage after the Final Smash ends.

However, it's easy to escape by just rolling out, although the victim must still be careful to not get hit by Luigi. The move is very useful in team matches if one of Luigi's partners is a hard-hitter (eg: Donkey Kong, Ganondorf, Ike, Bowser).

List of effects:
(The invincibility from respawning does not stop the effects from taking place)
 * Drastically reduced attack power
 * Weight reduction, therefore greater launch distance when hit, making a lot of Luigi's moves (such as his Smash attacks and Super Jump Punch) effective finishers even at very low percentages
 * Increased likelihood of Prat Falling
 * Flower growth on head, which causes damage
 * Dizziness as if shield broke (this can happen to aerial characters, which may KO them if not above a platform)
 * Uncontrollable taunting
 * Sudden sleepiness
 * Timeslow effect

Origin
The move is unique to Brawl. However, the name may be a reference to Luigi always being in his brother's shadow, the fact that Luigi was originally just a palette swap of Mario's color scheme, the Negative Zone bonus areas in Super Mario Bros 2, the infamous "Minus World" glitch in the original Super Mario Bros., the inverted overworld in Super Mario Bros. 2, or the fact that every color viewed through the bubble is changed into its false color.

Trophy Description
''Luigi's Final Smash. As exotic music plays, he performs a dance befitting a sorcerer's incantation. A barrier envelops him, negatively impacting all in his area. Random effects include getting launched, sleeping, moving in slow motion, tripping, fainting, and losing attack power. This technique is a reflection of the dark side he embraced in his brother's shadow.''

Trivia

 * If one faces a CPU Luigi and he uses Negative Zone, he will almost always only spam his Fireballs over and over again, even if his AI is set to Level 9. The CPU will start to use different attacks after the circle begins fading out.
 * If another trophy is placed directly in front of the Negative Zone trophy in the Trophy Gallery, some or all of the trophy will be inverted as well, depending on the trophy used. Likewise, if two Negative Zone trophies are juxtaposed in Trophy Gallery, the negative colors will cancel out and the overlapped space will be shown in positive color.
 * In a similar way, the big screens of Pokemon Stadium and Pokemon Stadium 2 will be double-inverted.
 * The Negative Zone trophy depicts four images of Luigi, with a single dozing Mario in the center.
 * The Negative Zone trophy is the only trophy to change the color of the Trophy Stand.
 * In the PAL version of Brawl, Luigi's final smash trophy has a different description. Instead of saying "This technique is a reflection of the dark side he embraced in his brother's shadow", it says "In contrast to the oddness of the dance, this is a terribly powerful Final Smash."
 * If a character gets a Screen KO while this Final Smash is used, the character falling will look negative, if falling where the camera shows Negative Zone is.
 * Despite Luigi's down taunt doing set knockback, it's still significantly more powerful in the Negative Zone, even powerful enough to OHKO lighter characters. This might mean that rather then making characters lighter, the Negative Zone decreases launch resistance.