Assist Trophy

The Assist Trophy, also formatted assist trophy, is an item in Super Smash Bros. Brawl, Super Smash Bros. for Nintendo 3DS / Wii U, and Super Smash Bros. Ultimate. It calls forth a random character to assist the player who used the item, similar to the Poké Ball item. This is unique in that the character released is from an actual Nintendo or third-party series, but is not playable. As a result, it introduces characters who did not make the cut as playable fighters.

Some Assist Trophy characters in Super Smash Bros. Brawl are unlockable, and almost every character is invincible; however, in Super Smash Bros. for Nintendo 3DS / Wii U and Super Smash Bros. Ultimate, all Assist Trophy characters are available from the start, and many characters can take damage and can even be KO'd (in the latter game, the opponent that defeats them earns a point), although characters that do not appear on the stage itself such as Andross and Nintendog remain invulnerable to attacks.

Players must be on the ground to summon an Assist Trophy's character. If a player is attacked and sent flying after grabbing the Assist Trophy, but before breaking it open, they must land before they can call forth the Assist Trophy's character. Only one Assist Trophy can appear at a time, unlike Poké Balls, except in Super Smash Bros. Ultimate.

Trivia

 * A concept similar to Assist Trophies was considered for Super Smash Bros. Melee, but the idea was scrapped due to development circumstances.
 * In the April 2014 Nintendo Direct focused on Super Smash Bros. for Nintendo 3DS / Wii U, the Waluigi Assist Trophy is used with the Wario series icon, instead of the Mario series icon. This is odd, since Waluigi has never appeared in any Wario series games. This was later changed, as seen on his Super Smash Bros. for Nintendo 3DS trophy.
 * In Super Smash Bros. for Nintendo 3DS / Wii U and Super Smash Bros. Ultimate, the figure in the trophy appears to be occasionally blinking.