Part 3 of JoJo's Bizarre Adventure gave us the first look at Stands; physical manifestations of one's soul which have many uses but are most commonly applied in battle. Though most of the characters Jotaro Kujo has allied with or fought against have impressive Stands at their disposal, some are not as nearly so admirable.
Many of those Star Platinum has come across have survived merely on account of the merits of the user, or in some instances, incredible strokes of blind luck. To contrast the hardship Jotaro encountered, fans must also analyze the weakest Stand users he has met in Stardust Crusaders.
10 Hol Horse
Hol Horse's "Emperor" Stand is a gun that can curve its bullet if it misses and hunt down its target. This makes him an exceptionally useful bounty hunter, especially when complemented by his natural skills as a marksman.
However, Emperor has extremely poor defensive ability, compelling Hol Horse to find companions by which to compound his own abilities. As an individual, he is incredibly vulnerable to attack and would struggle to take down a single one of Jotaro's allies, much less all of them at once.
9 Joseph Joestar
Joseph Joestar's "Hermit Purple" may be an excellent necessity to the team since it can track Dio's whereabouts at the expense of a camera or television, but on its own merits, it is not exceptionally strong.
Though it has mobility (since it can propel him forward like an elastic band), it lacks offensive striking power. Its defense is not particularly impressive either, though complemented by Joestar's Hamon, it is enough to ward off many melee attacks. Even still, he has rarely used it for this purpose, and it does not protect him against his opponents' projectiles.
8 Tennille
Tennille's "Dark Blue Moon" Stand is most effective underwater, providing situational usefulness much like High Priestess. This is even more restricting of the terrain he can attack his opponents since they are relatively safe once landlocked.
Further, Dark Blue Moon is not even particularly deadly underwater. When facing off against Kujo's Star Platinum at the bottom of the sea, he was nonetheless defeated with fairly little difficulty ~ even if his allies were too cowed by the razers on the water's surface to assist Jotaro's fight against him. Since Tennille's Stand fails even under its most favorable conditions, it evinces how weak it really is.
7 Boingo
Technically, Boingo's Stand should be among the most powerful of Dio's minions. It is able to predict the future with perfect clairvoyance, as he has often bragged to his partners.
However, these outcomes almost inevitably backfire for the fact that Boingo and his allies are completely incapable of taking out their quarry by themselves. If the Stand user was a more impressive physical threat, it would be more likely that his ability would have the desired effect, rather than turning on him in the most improbable and hilarious ways.
6 D'arby The Gambler
D'arbly the Gambler's Stand, Osiris, was able to reap the souls of his opponents, molding them into tiny chips and even able to divide them into portions to be wagered upon.
Though this may be a horrifying ability, the Stand itself is not able to protect its master. Consequently, Jotaro was able to intimidate D'arby with Star Platinum throughout the duration of their match, with the chips in his possession being the only thing preventing the game master from being pummeled into pulp. While Osiris serves its purpose to facilitate D'arby's skills, it is useless if its adversary does not agree to a gamble.
5 Nena
Nena's "Empress" Stand requires extremely specific circumstances to thrive. First, she must be close enough to someone to splatter her blood on them. Next, her target must not suspect the growth on their arm, nor look at it until it can manifest enough to defend itself.
Even after Empress has reached its full power, it is not particularly strong. Joseph Joestar was able to block its attack through his prosthetic hand (even if it would damage it), dunking it in a tank of fluid before killing it off. This would in turn destroy its user.
4 Mariah
Mariah's Stand, Bastet, affixes magnets to her opponents. This is virtually as useless as it sounds, especially when considering that her foes must physically touch the Stand (which looks like an electrical outlet) for it to take effect.
Though she may carry a large variety of weapons that increase the damage she can inflict, she was unable to significantly deter Joseph or Avdol from defeating her. Moreover, should Mariah be taken out quickly (which is a reasonable possibility since she has no defense to speak of), her Stand would deactivate and neutralize the threat she poses.
3 Oingo
Oingo's Stand allowed him to assume the visage of whoever he wanted. This placed him in an opportune spot to sabotage opponents and assassinate them before they were any the wiser.
There are two problems with his techniques, however. Not only is he a poor impressionist, his Stand does not disguise his outfit. Thus, if he needs to change his face in a pinch, he is immediately a target of suspicion. Ultimately, Oingo's incompetence would be his downfall, one of the few threats the Stardust Crusaders had disposed of without ever knowing his intentions.
2 Devo
Devo was the Stand user of "Ebony Devil," a tiny though malevolent doll which can carve up its enemies. The Stand is used mostly as a scout, waiting until its enemies are vulnerable before attacking them and rendering them incapable of fighting back.
However, should their quarry escape their immediate predicament, Ebony Devil has horrible offense, defense, and mobility. Since the damage Stands take are reflected back at their user, this spells that the doll becomes a safety hazard to its own master the second the fight is even.
1 Holy Kujo
Holy Kujo is one of the few Stand users completely incapable of controlling their power. Consequently, she quickly fell victim to it, her rapidly decreasing health forcing Joseph Joestar and Jotaro to embark on their quest to save her.
While others may be able to weaponize their Stands to increase their odds in battle, Holy's own ability operates much more as a debilitating curse. Her condition grew so desperate that she eventually even fell into a coma, rendering her powerless and evincing her poor strength of will.