Ratt

Ratt (ラット) is a stand used by two rats in Part IV: Diamond is Unbreakable.

Appearance/Personality
Ratt is an insentient machine resembling a shield. Josuke notes to himself that it's an unusually mechanical stand for a rat.

Abilities
Ratt can fire off barbed bullets, which will melt flesh upon impact for it to be formed like gelatin. This is very painful and would often lead to the death of one who falls victim to the bullets.

Trivia

 * Ratt is the only stand to be shared by two different people (in this case, rats) in the same Part.