The Koopatrol from Paper Mario. It wanders around randomly. If Mario comes close enough, it will use one of two attacks - go in its shell and chase mario, or attempt to ram him. To kill him, you get him to ram into a wall, and then jump on him while he is on his back, or run into him with a Star.
NOTE: WILL NOT WORK WELL WITH SLOPES!
Graphics ripped by Leod. No credit needed; to be assembled with Romi's Sprite Tool JackTheSpades's PIXI.