"A screw that holds Thunder Tower together. Even if 5 or 6 of them come loose, it's no big deal."
— Screwloose Battle Memory data

Screwlooses are enemies that appeared in the Chapter 5 portion of Mother 3 that appeared on Thunder Tower. Screwlooses have a relatively high attack stat but its low defense warrants an easy battle. Their primary elemental weakness is PK Thunder and their attack patterns can be majorly altered by the use of Brainshock.

Its battle sound is Battle Sound 44 which falls under Code Numbers 891 for regular attack, 892 for Smaaaash! and 893 for Miss. It has exclusively use of its battle sound.