The Alabasta arc was a One Piece story that revolved around Luffy's quest to return Princess Vivi to her desert homeland. After she had arrived, she would require the Straw Hat crew's assistance once again after realizing how far Crocodile and his Baroque Works agents' plot actually went.
It was easily the most difficult challenge that Luffy and his friends faced up until that point, with the renowned pirate captain losing against the feared Warlord on two separate occasions (arguably three, counting his first capture). By analyzing the toughest characters of the arc, a fuller understanding can be gained of the powers at work against one another.
10 Miss Doublefinger: The Voice Of Reason With Powerful Offense But Poor Defense
The partner of Mr. One, Doublefinger was the voice of reason among the Baroque Works agents that kept them from each other's throats. Her devil fruit power allowed her to turn any part of her body into spikes, and in a desperate situation, even inject herself to dramatically increase her physical strength.
While Doublefinger's powerful offense may make her a threat to Luffy (on account of her cutting ability), she has disappointing defense. This was seen through Nami's ability to defeat her in one strong hit.
9 Galdino / Mr. Three: His Treachery Overcame The Straw Hat Crew
Otherwise known as Galdino, Crocodile noted that Mr. Three's strength did not come from the power of his devil fruit; it was in his ability to fight underhandedly. The agent proved this true through his ability to defeat two giants, each with a bounty of roughly one hundred million on their heads.
Moreover, Galdino's treachery was able to overcome the entire Straw Hat crew, save Luffy (who struggled against his assistant, Miss Goldenweek) and Sanji (who was absent throughout the entire battle). This testament to his intelligence renders him a deadly adversary to contend with.
8 Nico Robin / Miss All Sunday: Strong Enough To Defeat Many But Lacks Durability
The vice president of the Baroque Works organization, Nico Robin's devil fruit allowed her to spawn her arms almost limitlessly. This allowed her to defeat dozens of trained marines, prevent the royal guards from storming the palace, and even overcome Alabasta's guardian, Pell (who in turn was able to survive an atomic explosion).
Nonetheless, she shares the same weakness as Doublefinger; her durability. When she and Crocodile turned on one another, the Warlord defeated her in seconds despite the water she had prepared to harden his body.
7 Sanji: Physically Strong Even Without A Devil Fruit
Sanji's physical strength has always been unusual for one without a devil fruit. Nonetheless, he applied it effectively during his fight against Mr. Two. Despite the ballerina's graceful skill and evident physical power (as he could keep up with Vivi's duck on foot and run up and entire cliffside), the chef was able to overcome him.
The only debilitating weakness that he displayed against his adversary was his unwillingness to strike women. Moreover, he would not even attack anything sharing Nami's likeness, granting Bentham significant leverage in their battle since he discovered this limitation and used it against him.
6 Daz Bonez / Mr. One: Can Turn His Entire Body Into A Gigantic Blade
Daz Bonez has clearly earned his title of Mr. One. His devil fruit power allowed him turn his entire body into a single gigantic blade, forcing Roronoa Zoro to rapidly improve his swordsmanship skills in order to stand a chance against him.
Moreover, the man is capable of crushing entire marble pillars with a single sweep of his hand. This proves that he possesses brawn to complement his ability, providing the only challenge Zoro might lose to (aside from Crocodile himself) out of all Baroque Works agents.
5 Roronoa Zoro: Overcame Mr. One With His Swordsmanship
A legendary swordsman even before joining Luffy's crew, Zoro's skill with his blades preceded him in his fight against Mr. One. Though he does not possess a devil fruit power, his discipline and focus grant him an edge against many foes that do.
He could easily defeat any Baroque Works agents he came across in an even fight, only struggling against Mr. One on account of his impossibly resilient body. Nonetheless, he overcame the villain through tenacity and grit despite the serious injuries he accrued in the process. Daz Bonez would have defeated anyone else in the crew, with the possible exception of Luffy himself.
4 Captain Smoker: Hard To Hit & Can Negate The Power Of Others
Smoker's devil fruit power makes it incredibly difficult for anyone to touch him. He can disperse himself into a dense fog, one that is capable of restraining his opponents and dangling them helplessly in the air.
Further, he carries a weapon with him that is able to negate the powers of others. It rendered him a serious threat against Luffy and gave him a fighting chance against Crocodile, should he be able to strike the Warlord before he can disperse into sand.
3 Crocodile: Versatile Fighter Who Defeated Luffy Multiple Times
One of the Seven Warlords, Crocodile's skill as a warrior is rivaled by his intelligence as a strategist. Through his design, he was able to plunge Alabasta into chaos, weakening it while its denizens worshipped him as a hero.
The villain's arsenal of weapons is vast and diverse. He can attack his foes with a noxious hook, crush them with sand, or even dehydrate their entire body in seconds, reducing them to a desiccated husk. Through these means, he was able to defeat Luffy multiple times despite the Straw Hat pirate being prepared to combat him with water in one of their battles.
2 Monkey D. Luffy: Ultimately Took Down Crocodile
As much as Luffy had struggled against Crocodile, he was ultimately able to defeat him. The Straw Hat would even accomplish this without the benefit of a barrel of water to sustain him, using his own blood as a catalyst in order to keep the villain solid.
Even after he had been poisoned and badly wounded, he found the strength to carry Alabasta's king and Nico Robin from the crypt once an antidote had been administered to him. It was an excellent demonstration of his tenacity and the true potential of the Gum Gum fruit.
1 Ace: Defeated An Entire Baroque Works Fleet With Ease
While he may not have actively fought against Crocodile's forces, Ace was easily the strongest character of the arc. A single stroke of his hand was able to decimate an entire fleet of Baroque Works ships, demonstrating the caliber of his attacks.
Since sand can be turned to glass if it is superheated, it follows that he would be able to defeat Crocodile without getting him wet first. Hypothetically, he would able to overcome his younger brother with similar ease, as Luffy's rubber properties do not protect him from overwhelming fire attacks.