"Hasn't noticed that its master is long gone, continues to bear his weight on its back."
Battle Memory

Rockin' Ghosts are enemies in Mother 3 that appear in the second floor of Osohe Castle, in a hall with mirrors. These enemies look like rocking toy horses being ridden by knight-like ghosts, which are only visible in the mirrors. They are first encountered by Duster in Chapter 2: Thief Adventure, and reappear up until Chapter 7.

These creatures attack by ramming, and they occasionally drop a Beef Jerky at the end of battle. They also have a very high Offense stat, but fighting two together will occasionally make one ram the other and damage them. No other enemy in the Mother series will perform this action unless under the influence of a Status Ailment.

Oddly, the text of the Battle Memory appears to refer to the rocking horse rather than the ghost riding it. This could be because the Japanese name "Obake Mokuba" literally translates to "Ghost Rocking Horse."

His battle sound is Battle Sound 1 which falls under Code Numbers 439 for regular attack, 440 for Smaaaash! and 441 for Miss.