From the Super Mario Wiki
Skuttler Cannoneers are enemies that appeared originally in Kid Icarus: Uprising and are common enemies in the Smash Run mode in in Super Smash Bros. for Nintendo 3DS. They do not run and are armed with an cannon. There are three different variants of their cannons as in the original game, one that shoots cannon balls, one will shoot a beam, and another one with shoot an homing missile at the player. Sometimes, their cannon malfunctions and shoots harmless confetti.
Super Smash Bros. for Nintendo 3DS Trophy information