Bumper

A Bumper is a throwable item that appears in every Super Smash Bros. game expect Super Smash Bros. Melee, which features the Flipper in its place.

Super Smash Bros.
In the original Super Smash Bros., it falls to the ground when thrown, causing one percent of damage to players who bump into it and weak knockback. There is also a Bumper floating above the Peach's Castle stage; this Bumper retains its original appearance and damage properties in the stage's return in Super Smash Bros. for Nintendo 3DS / Wii U and Super Smash Bros. Ultimate.

Super Smash Bros. Brawl
Bumpers return in Super Smash Bros. Brawl, replacing the Flippers from Super Smash Bros. Melee. Bumpers can also float in midair when thrown (making it possible to use them as deterrents for opponents trying to recover) and only damage players hit by the initial throwing. They no longer move if bumped into, although the knockback is far greater, and it increases as the target's damage increases.

Super Smash Bros. for Nintendo 3DS / Wii U
In Super Smash Bros. for Nintendo 3DS / Wii U, Bumpers have been redesigned; their outer part is silver instead of blue, and the central part is red with a yellow Super Smash Bros. symbol. This design is retained for Super Smash Bros. Ultimate. A Bumper trophy is featured in both games, but in Super Smash Bros. for Wii U, the trophy can only be obtained in Trophy Rush.

Super Smash Bros.

 * North American website: "Place the Bumper in the corner of the arena and toss your opponents onto it to send them flying."