The user creates a psychic field that can absorb certain projectile attacks (mostly energy-based rather than physical objects) to heal damage. The move lasts as long as the special button is held. Ness and Lucas' versions of PSI Magnet differ slightly in terms of speed, size, positioning, healing power, and auxiliary utility.
Ness's PSI Magnet is centered around himself and covers his entire body.
In Super Smash Bros., the move has very high starting lag, making it nearly useless and meaning it lacks practical use. However, the crowd releases very enthusiastic cheers for its successful use. In Super Smash Bros., the move recovers double the damage the projectile would have dealt normally.
In Melee, it is now blue instead of green. The move comes out 5 frames faster, but retains the same 30 frames of minimum absorption time and an additional 10 frames of ending lag before it can be dropped, making it a less than viable option.
In Brawl, the color changes again, from blue to a more purplish color. This move recovers about 1.6x (or one and two thirds) the damage the projectile would have dealt normally, and is the fastest of Ness' PSI Magnets. In SSB4 and Brawl, Ness's Magnet pushes enemies and some items (such as Snake's Hand Grenades) away from his body when released.
In SSB4, the move returns to its Melee-like blue coloring and is larger in size. In addition, due to certain explosions now being absorbable, it can absorb some previously troublesome items such as Bob-ombs (outside Sudden Death) and attached Gooey Bombs. As in Brawl, it heals 1.6x, but has a cap of 30% healed damage. Its end lag has been reduced in later patches of the game.
In Ultimate, the Magnet is largely unchanged in function, however it now features PSI graphics based on how PSI Magnet appeard in EarthBound. It now also slightly damages adjacent foes upon activation, ostensibly giving it a similar offensive use to the Reflector.
Lucas's PSI Magnet is centered around his outstretched hand: while it does not visibly cover his whole body nor the area behind him, Lucas will instantly turn around when hit from the back. Lucas's version of this attack also has a hitbox on his hand when released, which deals 9% damage and is a moderately strong semi-spike. This hitbox, however, doesn't have much practical use, due to the delayed nature of it and its extremely small hitbox making it very difficult to land, but tactical use of it can bait opponents and its horizontal knockback can prove effective in certain circumstances. Additionally, Lucas recovers more percentage than Ness when he absorbs a projectile (2.5x the damage the projectile would have dealt normally, a 56% improvement over Ness's). Its startup and ending lag are much lower than Ness's version.
In SSB4, Lucas's PSI Magnet once again heals 2.5x damage, but with a cap of 30% healed damage. It also has a larger hitbox, but it only deals damage if the opponent is in the center of the magnet. It also deals slightly less damage than it did in Brawl. In addition, Lucas no longer turns around when hit from behind, decreasing the move's range and overall practicality.
In Ultimate the move is largely unchanged, however like Ness's it features EarthBound like PSI graphics. PSI Magnet no longer halts Lucas's momentum when used airborne, much like how it worked in Brawl. Is endlag has also been reduced making it safer to use.
When used in the air, this move will cancel any vertical/falling momentum temporarily. This allows for this move to be used as a pseudo-SHFFL if used immediately after a jump, or a pseudo-wavedash if the player activates the move at a downward diagonal angle. Using C-sticking special moves control scheme for the Gamecube Controller, this move, used right after PK Fire for Lucas, will allow the wavedash to work much more easily.
This move is very useful in Team Battles with Friendly Fire on, as a teammate can use their projectiles to heal Ness or Lucas. This is often used in doubles by Ness or Lucas players, who can team up with characters who have fast, damaging projectiles (e.g., Lucario or Bowser) to heal themselves. As of version 1.1.3 in Super Smash Bros. 4, the amount of damage healed when absorbing a fellow teammate's projectiles is cut in half.
When a projectile is absorbed, if the player taps the control stick or control pad (depending on controller) in a direction, Ness and Lucas will either roll in that direction, sidestep, or jump without having to release the attack first.
In the original Super Smash Bros., CPUs level 5 and above will almost never use the Fire Flower against Ness because he can absorb the fire with PSI Magnet. Instead, they will throw the Fire Flower at him. This also applies to Fox, as he can deflect the fire with his Reflector.
The attack can be put to significant use on the Corneria stage by absorbing the Great Fox's lasers. However, if Ness or Lucas touch the cannons while they are "charging", it is almost guaranteed to KO them. Only the actual laser shots can be absorbed.
Special Move customization was added in Super Smash Bros. 4. These are the variations:
Like the other DLC characters, Lucas has no custom move variations.
PSI Magnet appears in all three EarthBound games. However, neither Ness nor Lucas can use it in their source games; instead, PSI Magnet is learned by some of their friends and party members, Paula and Poo in EarthBound and Kumatora in Mother 3 respectively.
In all three of the EarthBound games, the move involves the user absorbing an enemy's Psychic Points (PP) and adding it to their own PP: PSI Magnet drains 10 PP in Mother and 2-8 PP in EarthBound and Mother 3. It does not, however, absorb incoming attacks, that being a property of PSI Shield. As PP are not a mechanic in the Super Smash Bros. series, PSI Magnet recovers a small amount of health instead: this could be a reference to the healing technique Lifeup which, unlike PSI Magnet, is available to both Ness and Lucas in their respective games.