Assist Trophy

An Assist Trophy is an item that, when grabbed, summons a character out of twenty seven choices of various origin to quickly aid the holder, though there are currently three third party Assist Trophies, not to mention some assistants get in the way more than they help. Assist Trophies work nearly identical to Poké Balls. However, no Pokémon come out of them, and once an Assist Trophy is grabbed, it is automatically activated (though this is not very convenient), assuming the holder is standing on the ground, and not in a jump, attack, or hitstun. Some assist trophies must be unlocked in order to be used, such as Isaac from Golden Sun. Unlike the Poké Ball, this can be eaten.

Only one Assist Trophy (and the character it releases) can be in a match at once. The next Assist Trophy will not appear until the data for the character it will release is fully loaded.

List of Assist Trophies in Super Smash Bros. Brawl

 * Andross - Andross appears in the background and shoots tiles at the players.
 * Barbara - Barbara strums on her guitar creating damaging soundwaves, similar to Konga Beat, but with less range and duration. Unlock: Obtain twenty five Songs.
 * Devil ("Demon" in Europe) - Devil moves the stage boundaries. However, Hoop Damage is not added if you are out of the boundaries the Devil creates.
 * Dr. Wright - Doctor Wright summons buildings to rise up out of the ground. This damages opponents who are standing in the area of the building, and produces great vertical knockback. Occasionally makes a massive skyscraper.
 * Excitebikes - Excitebike racers ride around the stage causing damage to those they collide with. Some of them, if on a stage with an edge, will go back and forth until their time runs out.
 * Gray Fox ("Cyborg Ninja" in Japan)- Frank Jaeger, the Gray Fox, runs around slashing opponents. Also reflects stray projectiles. Unlock: Unlocked with Snake
 * Hammer Bro - Hammer Brother throws hammers at opponents.
 * Helirin - Helirin floats around the stage while rotating, acting as a wall.
 * Infantry &amp; Tanks - The Advance Wars infantrymen and tank sprites roam across the stage shooting at players. When spawning, they follow the direction of the summoner. Unlock: Play 300 Brawls
 * Isaac ("Robin" in Japan) - Isaac pushes opponents off the stage by using a skill called Move, represented by giant magic hands. It can be dodged and escaped. However, escaping is just about impossible unless you're on the tip of the hand. Unlock: Play 200 Brawls
 * Jeff - Jeff Andonuts shoots 5 homing rockets from his Multi Bottle Rocket five invention (four small and one large) at his opponents.
 * Jill ("Dori Kururi & Rasanda 8" in Japan) - Jill attacks opponents with her drill.
 * Kat & Ana - Kat and Ana fly in different directions slashing at anybody in front of them, but always cross in the same spot.
 * Knuckle Joe - Knuckle Joe delivers a series of Vulcan Jabs to his opponents and finishes with either a Smash Punch or an uppercut attack named Rising Break.
 * Lakitu and Spinies ("Jugem" in Japan) - Lakitu drops Spinies onto the field. Upon landing, the Spinies walk around giving damage to opponents. Lakitu can be knocked off the screen or killed.
 * Little Mac - Little Mac runs around punching opponents.
 * Lyn - The screen darkens, as Lyn focuses and then having teleported, she delivers a single, powerful strike focused on the nearest opponent, similar to Galaxia Darkness in animation and knockback.
 * Metroid - A Metroid latches onto players and gives them damage. Can be attacked and shaken off, but prevents the victim from using recovery moves. However if done right, the character can spam recovery moves indefinitely until the Metroid disappears.
 * Mr. Resetti - Mr. Resetti gives speeches about different topics. If attacked, he will keep talking. If attacked too much, he causes an explosion.
 * Nintendog - A "Nintendog" (Labrador Retriever) blocks the screen.
 * Ray MK III - Ray MK III flies around the stage shooting missiles and green energy bullets. Unlock: Play 100 Brawls
 * Samurai Goroh - Samurai Goroh slashes his swords while chasing opponents.
 * Saki - Saki Amamiya slashes and fires with his Dolphin Gun.
 * Shadow the Hedgehog - Shadow slows down time with Chaos Control, similar to the Timer item, but with shorter duration. The summoner continues to move at normal speed. Unlock: Unlocked with Sonic
 * Starfy (known by its JP name, Stafy in the game) - Starfy spins, hurting players. Can be knocked off stage.
 * Tingle - Tingle randomly summons a variety of strange effects (see article)
 * Waluigi - Waluigi repeatedly stomps players into the ground. This onslaught is followed by either a strong kick or a strike from his tennis racket.

In addition to the above characters, scrapped Assist Trophy data for Ridley was found when hacking Super Smash Bros. Brawl. Attendants at the 2007 Whobby Game Festival claimed to have seen Assist Trophies of Duster, Muddy Mole, and Rosalina, but this was proven to be fabricated upon the release of the game.

List of Confirmed Assist Trophies in Super Smash Bros. (Wii U and 3DS)
Sakurai has stated that some Assist Trophies will be exclusive to certain versions.
 * Andross - Andross appears in the background and shoots tiles at the players.
 * Ashley - Ashley possesses a purple cloud that will make anyone in the dark zone take damage and possibly end up buried in the ground. If someone eats food in the dark zone, they will receive damage.
 * Chain Chomp - Chain Chomp can try to reach to the opponent quickly to attack him or her.
 * Color TV-Game 15 - 2 paddles from the video game "Pong" appear on the edges of the screen, hitting a ball back and fort that can injure players. Further details unknown.
 * Dark Samus - Dark Samus is seen shooting beams rapidly and unveiling blue tentacles around her.
 * Devil ("Demon" in Europe) - Devil moves the stage boundaries. However, Hoop Damage is not added if you are out of the boundaries the Devil creates.
 * Dillon - His attack involves rolling a quick charge. Further details unknown.
 * Dr. Kawashima - He flings bubbled numbers at the fighters, which can be attacked to change their direction. When they collide and form a "10", a giant explosion occurs.
 * Dr. Wright - Doctor Wright summons buildings to rise up out of the ground. This damages opponents who are standing in the area of the building, and produces great vertical knockback. Occasionally makes a massive skyscraper.
 * Elec Man - Elec Man shoots his signature Thunder Beam horizontally and vertically.
 * Ghirahim - Ghirahim moves acrobatically across the stage, attacking with a sword and knives. Should he be knocked off of the stage, he possesses the ability to teleport back.
 * Hammer Bro - Hammer Bro throws hammers upwards to the opponents by either standing or jumping.
 * Isabelle - Isabelle will toss various fruits at the one who summons her, healing them upon touch. Should a fruit be intercepted by an opponent, they will be healed instead.
 * Knuckle Joe - Knuckle Joe delivers a series of Vulcan Jabs to his opponents and finishes with either a Smash Punch or an uppercut attack named Rising Break.
 * Lakitu and Spinies - ("Jugem" in Japan) Lakitu drops Spinies onto the field. Upon landing, the Spinies will walk around giving damage to opponents. Lakitu can be knocked off the screen or be killed.
 * Lyn - The screen darkens, as Lyn focuses and then having teleported, she delivers a single, powerful strike focused on the nearest opponent, similar to Galaxia Darkness in animation and knockback.
 * Magnus - Magnus attacks by swinging his sword, and jumping and then swinging his sword. He can be stopped by being attacked.
 * Metroid - A Metroid latches onto players and gives them damage. Can be attacked and shaken off, but prevents the victim from using recovery moves. However if done right, the character can spam recovery moves indefinitely until the Metroid disappears.
 * Midna - Midna uses her hair to grab an opponent and swing him or her at any part of the stage.
 * Mother Brain - Appears in a beaker and shoots a rainbow-colored laser from it's eye. She is also protected by Rinka enemies. If attacked enough, she can be defeated.
 * Nintendog - A "Nintendog" (French Bulldog) blocks the screen.
 * Nightmare Wizard - Nightmare Wizard appears as the power orb before reverting to his wizard form, upon which he engulfs the screen into complete darkness. This effect causes players to attack blindly.
 * Phosphora - Phosphora soars through the air at a high speed, shooting lightning bolts. She can't be defeated, but attacking her will cause her to flinch.
 * Prince of Sablé - Transforms into a snake or a frog, and unloads multiple attacks on any opponent he catches.
 * Riki - Attacks using Arts such as Happy Happy, Freezinate, and Yoink! It is currently unknown what effect each of these abilities has.
 * Saki - Saki Amamiya slashes and fires with his Dolphin Gun.
 * Samurai Goroh - Samurai Goroh slashes his swords while chasing opponents.
 * Shadow the Hedgehog - Shadow slows down time with Chaos Control, similar to the Timer item, but with shorter duration. The summoner continues to move at normal speed.
 * Skull Kid - Skull Kid can turn the arena upside down.
 * Starfy (known by its JP name, Stafy in the game) - Starfy spins, hurting players. He can be defeated if attacked enough.
 * Takamaru - Takamaru uses his Multidirectional Pinwheel Knife Rook Attack.
 * Tingle - Tingle randomly summons a variety of strange effects (see article).
 * Waluigi - Waluigi repeatedly stomps players into the ground. This onslaught is followed by either a strong kick or a strike from his tennis racket.

Trophy Description
''A capsule that contains characters who will help you out in battle. You won't know who's in the capsule until you open it. It may be someone everyone knows or someone who's a bit of a mystery. The majority of these characters are invulnerable, so attacking them is not an option. You know what that means, right? RUN!''

Trivia

 * Hammer Bro. is the only Assist Trophy character to appear as an enemy in the Subspace Emissary.
 * In Classic Mode, if the character who summoned an assist trophy dies, the assist trophy goes away. However, this does not happen in All-Star mode.
 * In the Gamecube preview issue of Electronic Gaming Monthly, the Smash Bros Melee article comments that Nintendo originally tried to implement Assist Trophies in Melee. The only trophy concept they gave details on was one that would release the ducks from Duck Hunt to fly around the stage and interfere with the fighters.