Nami is also a competent fighter, although among the weakest in the crew. She mainly makes use of her wits in combat to get the better of her enemies. Surprisingly, One Piece 1058 showcased her using Conqueror's Haki in what appeared to be a gag scene.
Jinbe notes that Nami is currently displaying Conqueror's Haki while yelling at Luffy. This might seem like a gag at first but upon further inspection, Nami'ss rage actually is producing a small amount of black lightning, the series's main way of illustrating Conqueror's Haki whenever it shows up.
All members of the Monster Trio possess Haki, with Luffy and Zoro possessing all three types and achieving advanced applications.
Despite that, Robin has featured in few battles, with her last true one-on-one happening at Skypiea! Robin has gotten powerful, but she doesn't seem to possess the ability to use Haki for now. Just like Nami, Robin will likely encounter some strong foes at Wano Country which will require her to be able to use Haki.
Though she has not yet displayed the ability to use Haki, Robin is fully aware of the power as she commented on Luffy knocking out half of Hody's men. She also has great knowledge about Haki, such as explaining the principles of Busoshoku Haki to Franky when Luffy fought Caesar Clown.
Nami doesn't have any Haki, however, along with her partner Zeus, she was strong enough to take on a member of the Tobiroppo, Ulti, without much trouble. Surprisingly, Ulti could use two Haki types with great efficiency but lost to Nami and Zeus anyway.
Sanji is an extremely skilled Haki user. During the two years he spent at Maiden Island, he trained his usage of both Armament and Observation Haki. Unlike Zoro and Luffy, Sanji wasn't taught this skill by anyone. He managed to learn all by himself and that is certainly an incredible feat.
As fans know, Nami doesn't wield any form of Haki in the story so far. Haki is a power that Rayleigh described to be the manifestation of the user's spirit. Every person in the One Piece world possesses Haki, however, not everyone is able to bring this latent skill out.
It's no surprise that Luffy possesses the power to use all three types of Haki, being someone who aims to become the Pirate King. In fact, Luffy has successfully taken his Armament and Observation Haki to extreme levels, making him a magnificent pirate in the process.
Luffy has mastered all three types of haki, including Kenbunshoku Haki (Observation Haki), Busoshoku Haki (Armament Haki), and Haoshoku Haki (Conqueror's Haki). He can even use several subforms of the hakis, which makes him one of the most powerful haki users in the One Piece world.
The first character to appear in One Piece CAPABLE of Armament Haki Was Red-Haired Shanks and probably most of his crew as well, during Luffy's flashback.
4/12 Armament Haki Subtype 4: Advanced Ryuuou
So far, only two characters have shown the ability to use it, Rayleigh being one, and Monkey D. Luffy being the other. Although Rayleigh seemed like an expert at using it, Luffy has only managed to use it subconsciously.
One Piece's weakest Conqueror's Haki user is undoubtedly Eustass Kid. He's shown no signs of training or skill with the technique, as well as showing no signs of Advanced Conqueror's Haki. While it's likely he eventually becomes more skillful with it, Kid currently ranks as the weakest user of the form in the series.
Kenbunshoku Haki, one of the three Haki types in One Piece, grants the most powerful pirates unfathomable abilities. From sensing people's morality and emotions to being able to predict movements in battle, this form of Haki allows users to tap into a sixth sense that provides impressive precognitive abilities.
Dragon is almost certainly going to be a user of Conqueror's Haki as well just like his son. In Marineford, Luffy's Conqueror's Haki was attributed to Monkey D. Dragon, meaning he is already implied to be its user despite not having used it so far. In the future, fans will certainly see him make use of this ability.
Busoshoku is perhaps Luffy's most used Haki as he commonly mixes it with his Devil Fruit abilities to increase his offensive and defensive potential.
Haki is apparently quite difficult to master, as Rayleigh stated that two years was not enough time to learn the basics, though several characters managed to master it within the timeskip, including Luffy, Zoro, Sanji, Tashigi, Smoker, Koby, and Bellamy.
After the Straw Hats escaped from Totto Land and Nami revealed that she keeps Zeus in her Clima-Tact, it was shown that Zeus apparently did not mind working for Nami. However, when Big Mom was later able to use her power to regain control of Zeus, Nami stated that their friendship was over.
Haki. How Usopp sees things using Kenbunshoku Haki. Usopp has awakened his Kenbunshoku Haki during the latter half of the Dressrosa revolt, as he was able to see auras of Luffy, Law, and Sugar, who were in the royal palace, from the old King's Plateau near the Corrida Colosseum.
Monkey D. Luffy has mastered all three types of haki, including Kenbunshoku Haki (Observation Haki), Busoshoku Haki (Armament Haki), and Haoshoku Haki (Conqueror's Haki). He can even use several subforms of the hakis, which makes him one of the most powerful haki users in the One Piece world.
Yes he can. He can use all 3 types of haki, being armament, observation and conqueror haki.