Bulborbs will use a slam attack if there's a fighter behind them. It can hurt a lot, but it also leaves the Bulborb open to counterattacks.
Bulborb is the fictional enemy in the Pikmin Universe, who devour Pikmin. In Super Smash Brothers, Bulborbs first appeared in Super Smash Brothers Brawl as both a stage hazard and trophy. Bulborbs return in Brawl's successor, Super Smash Brothers 3DS/Wii U.
 Super Smash Brothers Brawl
Bulborbs play a minor role in Brawl, acting as a stage hazard in Distant Planet and a collectible trophy. As a stage hazard, a Bulborb can be used as a standing platform -- but not for too long. Standing on a Bulborb for too long will prompt the Bulborb to charge or swallow you, killing the player.
 Super Smash Brothers 3DS/Wii UBulborbs return as a stage hazard in Distant Planet but are added to the new game mode Smash Run as popular enemies. Bulborbs are shrunken down in size but still remain difficult to kill. Bulborbs will not be stunned when attacked, and will persistently charge at players.