Mega Mushroom

The Mega Mushroom is an item introduced in Mario Kart Wii. It grows the user to a massive size and allows them to flatten other players. The item has recently returned in HammerBro101's fan-made installments of Mario Kart. Its opposite is the Mini Mushroom, which shrinks the user. Prior to appearing as a Mario Kart item, it debuted as a power-up in New Super Mario Bros., where it allows the player to destroy everything in their path.

Mario Kart Wii (2008)
The Mega Mushroom makes its Mario Kart debut in Mario Kart Wii, where it can be obtained from 4th to 8th place. In addition to growing bigger, the player grants the ability to flatten other players by running over them, making them lose their items. The player is immune to all item attacks except Stars and Bullet Bills. If a Mega driver is struck by Lightning, that racer will return to normal instead of becoming small.

Koopa Kart Wii (2010)
The Mega Mushroom is a new item to the Koopa Kart series in Koopa Kart Wii, functioning as it did in Mario Kart Wii. It is obtainable from 5th to 11th place.

Koopa Kart Tour (2020)
After its absence from Koopa Kart 7 and Koopa Kart 8, the Mega Mushroom returns in Koopa Kart Tour, serving the same purpose as in Koopa Kart Wii. However, the user grows slower, though they can avoid Bullet Bills. The item is obtainable from 4th to 8th place.

Trivia

 * Like the POW Block and Thunder Cloud, the Mega Mushroom has been absent from two Mario Kart games, spanning an 11 year absence from Mario Kart Wii (2008) to Mario Kart Insanity (2019).