Poison Mushroom

The Poison Mushroom (, Poison Mushroom) is an item from the series.

Origin
Poison Mushrooms made their debut in  and has become a recurring item in later Super Mario games. They are mushrooms that deceptively resemble the Super Mushroom, but with a duller color scheme and angry eyes. In Super Mario All Stars and , the Poison Mushroom's cap was redesigned, featuring a skull-faced pattern, with a purple cap in the former and a blue cap in the later. Later games in the Super Mario series starting with  adopted a purple magenta spotted cap, abandoning the skull design in the process.

Poison Mushrooms are known for being a harmful variety of Mushrooms where touching one will cause the player to take damage or lose a life. In the Japanese Super Mario Bros. 2 and its later re-releases, if a player was Fire Mario or Fire Luigi and came into contact with a Poison Mushroom, they go immediately to their small forms, though this doesn't apply in Super Mario 3D Land. If a player in their small forms comes into contact with one, then they will lose a life. In Super Mario 3D Land, they follow the player around, like the s in said game.

The, introduced in ' (better known for their appearance in the ' series), has an identical function to Poison Mushrooms as they are depicted in Smash, but are treated more as regular power-ups than a threat, allowing Mario or Luigi to have floatier movement and, the ability to squeeze into tighter areas. Despite this, a single hit will cause the player to lose a life.

As an item
The Poison Mushroom debuted as an effect item in Super Smash Bros. Melee. It will appear on the stage and keeps sliding to the right. In Melee, it will slide left if it spawns on the right half of the stage.

The player's fighter will shrink smaller after touching it, which also feature the following effects: The transformation lasts about ten seconds. Touching another Poison Mushroom will reset the timer. Touching a Poison Mushroom while under the effect of a Super Mushroom and vice versa will restore a character to their normal size, whereas the effects of Lightning are canceled.
 * Decreases the player's fighter's hitboxes and hurtboxes.
 * Decreases the player's fighter's weight by a small amount (applies a 0.7× multiplier in Ultimate).
 * Increases the fighter's knockback taken multiplier. This consequently makes the fighter more vulnerable to attacks that have high base knockback values.
 * Decreases the damage dealt by direct attacks (by 0.6x from Brawl onwards, while the damage drop is less severe in Melee) and subsequently less knockback.
 * Most projectiles still deal their base damage amount, but they will be smaller and have decreased range during the item's effect. This also applies to some other unique attacks, such as Hammers.
 * The base knockback and knockback growth values are not affected.
 * Decreases the distance and damage dealt by throwing items.
 * Decreases the character's jump height proportionally.
 * Decreases the character's falling speed and air speed.
 * Decreases the character's walking and dashing speed.
 * Decreases the landing lag of the character's aerial attacks.
 * Decreases the distance gained by the character's recovery moves in Melee.
 * The character's sound effects and voice become higher-pitched and sped up. This does not affect gameplay.

In Super Smash Bros. Brawl, the Poison Mushroom has been updated to match the Super Mushroom's modern design from this game, while also retaining the slightly darker coloration. Along with this, they now have angry eyes, a trait that would later be used in .

In Super Smash Bros. Brawl and Super Smash Bros. 4, the fighters strike a pose while growing/shrinking, briefly lamenting their reduced size and relishing their return to normal size. Most of the items held by the player, as well as their own projectiles, will be proportionate to their lower size. Certain attacks or charge ups can be interrupted if a Poison Mushroom touches the player in the course of doing an action.

In Super Smash Bros. Ultimate, the fighters no longer strike a pose when they're growing or shrinking, making their animation similar of that to Melee. This also prevents certain attacks and animations from being interrupted when a player touches one.

Tiny battles appear as a feature in Melee's Special Smash and in later games onward, where all fighters become tiny under the permanent effects of a Poison Mushroom. In Brawl's Tiny Special Brawl, direct attacks deal around 0.48x their normal damage, and pitch can now be altered further. In Smash 4's Tiny Special Smash, fighters still deal 0.48x their normal damage with their direct attacks, but unlike in Brawl, they do not receive an increased knockback taken multiplier. If players acquire a Poison Mushroom in that game mode, their direct attacks will deal 0.34x their normal damage. In a Giant Special Smash, acquiring a Poison Mushroom lowers a fighter's damage multiplier to 0.92x.

Also, in Ultimate's Spirit Battles, players can battle a puppet fighter that is either tiny or occasionally becomes tiny.

In Smash Tour
The Poison Mushroom appears as a red trophy item. When used, it makes the player's fighter start the battle in tiny form. Using this trophy cancels the effect of a Super Mushroom trophy used by the target.

The Poison Mushroom is one of the items that can appear during a Transformation Smash.

In Super Smash Bros. 4
The Poison Mushroom trophy appears in both versions. In, it is part of the Super Mario Bros. 2 & 3.

Trivia

 * Although being mini reduces one's ability to recover, certain up specials which are affected by a fighter's gravity stat will actually go higher as a result of the reduced gravity applied by the mushroom.
 * While other items are usually designed to visually stay true to their home series in subsequent Smash titles, the Poison Mushroom is the only item from another series's universe that is deliberately given an original design for the Smash series. Here, it is visually similar to the Super Mushroom instead of the purple hue it is known for in recent Mario games. This is done as an attempt to confuse fighters, similarly to its original appearance in Super Mario Bros.: The Lost Levels in which it was a different color but does not look overtly threatening, disguising its deadly nature.
 * The Melee trophy of the Poison Mushroom states that the Poison Mushroom made its debut in Super Mario All-Stars, but its first appearance actually was in the Japanese version of Super Mario Bros. 2; this could be because Super Mario-All-Stars was technically the first game in the west to include the Poison Mushroom. This was later corrected in Brawl, using the western title of Super Mario Bros.: The Lost Levels. Conversely, Smash Wii U also lists Super Mario Bros.: The Lost Levels, however, like in Melee, it tracks its western appearance on "08/93", the release date for Super Mario All-Stars, rather than the original Japanese release date.
 * In Brawl, if uses Quick Attack on a falling Poison Mushroom or Super Mushroom, it will perform the size change super jump.
 * In Brawl, Pikmin Throw uniquely won't change pitch upon growing or shrinking.
 * In SSB4, although Pikmin grow and shrink with Olimar, the pitch of Pikmin depends on what size they were when plucked, and this pitch persists even after further size changes.
 * In Ultimate, the sounds of tiny opponents in several Spirit Battles may play at their normal pitch instead of sped up as usual for unknown reasons. This appears to happen frequently when the conditions "The enemy is tiny" and/or "Tiny [character]" are not listed on the Spirit Battle preview screen; an example can be seen with the tiny puppet fighter appears in the Young Zelda Spirit Battle. This is also true for the Spirit Battles involving giant puppet fighters.