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.
Zoro is a very powerful fighter and he possesses all three types of Haki. Zoro was able to use Conqueror's Haki unknowingly against Kaido. Biggest Feat: With his newfound power, Zoro managed to defeat the right-hand man of Kaido, however, his biggest feat is scarring Kaido.
1) Charlotte Katakuri
Despite losing to Luffy during Whole Cake Island, Charlotte Katakuri is without a doubt the series' strongest Observation Haki user.
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.
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.
Haoshoku Haki is a rare form of Haki that allows the user to exert their own willpower over others. This type of Haki cannot be attained through training and only one in several million people are born with this ability.
Those who have mastered the fourth form of Haki will be able to manipulate nature as they see fit. They can cause living organisms to grow rapidly or die rapidly (though not resurrect them), and make objects move with the force of their minds, akin to telekinesis.
Edward Newgate, or Whitebeard, was once the strongest man in the world of One Piece. He was an adept user of all three types of Haki, and as the most powerful of the four Yonko, it goes without saying that he mastered the use of Conqueror's Haki as well.
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.
Garp's Armament Haki is of the highest caliber. He defeated the infamous pirate Don Chinjao with just one enhanced punch. Garp's ability to utilize his Haki is so extreme that he used to destroy mountains for training. His rank in the Marines doesn't do his powers justice.
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.
He is a specialist of Observation Haki, Ryuo, and also Conqueror's Haki. Among all the Haki types, however, Luffy is especially skilled at using Conqueror's Haki, which is his best Haki type.
Haki is a mysterious power that allows the user to utilize their own spiritual energy for various purposes. It can be used to sense people's spiritual energy and predict their actions, give the user a protective coating of spiritual energy, and, for a certain group of "chosen ones", overpower the willpower of others.
During the Raid on Onigashima, Luffy's recently heightened mastery of advanced Busoshoku and Haoshoku Haki allowed him to fight on par with Kaidou of the Four Emperors before awakening his Devil Fruit's true power upon suffering a third defeat from a finishing blow, which finally allowed him to emerge victorious ...
The Armament haki (busoshoku) is the ability to project your spirit into armor. An example of how it represents one's spirit is Vergo's purple haki as per debut. Vergo maybe mastered his armament haki. So this purple tint to his haki could've been his spirit's nature, the same to Luffy where he got his own shade.
White Haki spirit color is the rarest color and cannot be obtained with robux.
The Haki Haki no Mi (覇気覇気) is a Paramecia-type Devil Fruit in which the user is able to see all three types of Haki, as symbolized by a different color. Haki (覇気) meaning “Ambition”, in both Viz Manga, and the FUNimation dub called the Color-Color Fruit and it was eaten by Gozu.
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.
All members of the Monster Trio possess Haki, with Luffy and Zoro possessing all three types and achieving advanced applications.