In the current events at Wano, apart from Luffy, there are formidable contenders capable of facing Admiral Ryokugyu. Let's explore these remarkable individuals.
One Piece chapter 1053 introduces the visage, character design, and a glimpse of the formidable strength of the new character, Admiral Ryokugyu of the Marines. Surprisingly, this character idolizes Akainu and aims to take down Luffy to earn praise from their superior.
Many fans have eagerly awaited the clash between Luffy and Admiral Ryokugyu in the upcoming parts of the Wano arc. However, not only the captain of the Straw Hat crew, but the following 6 characters are fully capable of confronting Admiral Ryokugyu in a battle. Let's delve into them!

Marco
A highly esteemed figure in the pirate world, the Phoenix Marco arrives in Wano with the intention of aiding Luffy and the alliance against Kaido. Currently, besides a brief encounter with Big Mom, he has yet to showcase his full strength against the two strongest commanders under Kaido, King and Queen, as the former captain of the Whitebeard Pirates' first division.

This is why Marco currently appears formidable, combining his already formidable strength with the Mythical Zoan Devil Fruit's exceptional regenerative capabilities. He poses a challenging adversary for Admiral Ryokugyu, given his abilities and combat experience. Marco has the capacity to hold his ground against an admiral, a feat he demonstrated in the all-encompassing battle of the navy.
Yamato
Many fans have been eagerly anticipating Yamato's entry into Luffy's crew, taking on the role of Oden. Her journey mirrors Oden's from over 20 years ago, joining forces with the future Pirate King Luffy to conquer the Grand Line and discover the One Piece treasure.

In the Wano battle, Yamato faced off against her father, Kaido, on even terms and emerged without any serious injuries. Possessing the rare Mythical Zoan Devil Fruit power and enhanced physique from Kaido's genes, Yamato would be an intriguing adversary if Admiral Ryokugyu intends to approach Luffy. A clash between Yamato and Ryokugyu would serve as a daring test for her to showcase her strength.
Law
Currently, the death-defying surgeon Law has a bounty of 3 million beli, equal to Luffy's. With the awakened power of his Devil Fruit, Law wields a formidable internal body attack. Even someone as resilient as Big Mom feels perplexed against Law, making Ryokugyu's encounter with this character no easy feat.

In addition to strength, Law's intelligence and combat experience will play a crucial role in countering Ryokugyu if the admiral attacks the victory celebration of the alliance taking place at Flower Capital.
Kid
Speaking of Law, we can't overlook Kid, who also plays a vital role in the Wano battle. With the awakened Devil Fruit power and new insights into Conqueror's Haki, combined with advanced Armament Haki, it won't be easy for Ryokugyu to defeat this Supernova.

Currently, Kid is quite displeased with Luffy being promoted to one of the Four Emperors while their bounties are equal. Given his personality, it's not surprising if Kid aims to outshine Luffy and confront Ryokugyu if the admiral truly arrives at the victory celebration.
Zoro and Sanji
Always pivotal characters in the story, Zoro and Sanji's contributions in the Wano battle are undeniable. The author, Oda, has bestowed power-ups upon these two stalwart arms serving under Luffy.

Currently, Zoro and Sanji individually face a formidable challenge in defeating Admiral Ryokugyu. However, they possess the capability to hold off the adversary and create opportunities for their crew to safely depart Wano. Together, the synergy of Zoro and Sanji can effectively thwart Ryokugyu, making it challenging for the admiral to achieve his goal of reaching Luffy.
In general, aside from Luffy and the six individuals mentioned earlier, the alliance that just defeated Kaido and Big Mom is fully equipped to impede a Marine admiral like Ryokugyu. What are your thoughts on this? Feel free to share your opinions!
