Rolling Crate

A Rolling Crate is an item featured in every Super Smash Bros. game starting with Super Smash Bros. Brawl. Although it is technically a Crate, its effects greatly differ. Once hit, instead of being destroyed and expelling items, the Rolling Crate will begin to travel about on its wheels. It will run over any player in the way, damaging them. Players can stand on top of it as it rolls by, unlike regular Crates. If attacked with enough force, they can be broken open to release items.

Super Smash Bros. for Nintendo 3DS / Wii U
In Super Smash Bros. for Wii U, the Rolling Crates trophy is only obtainable in Trophy Rush.