Marijoa is the domain of the Celestial Dragons, who are the descendants of the founding families of the World Government. Naturally, they hold a great deal of authority. The Celestial Dragons can do whatever they want without ever facing any repercussions. Given their importance, Marijoa is always crawling with high-profile fighters to ensure the safety of the Celestial Dragons.
During the most recent Reverie, the security was increased further as kings and queens from all over the One Piece world were visiting the Holy Land. The Reverie turned out to be quite eventful, and Marijoa ended up becoming a battleground. With so many powerful One Piece characters on display, it was truly a spectacle. However, some of them were clearly stronger than the rest.
8 The Revolutionary Commanders
Sabo was not alone when he infiltrated Marijoa. He was supported by Morley, Karasu, and Lindbergh, who are commanders of the regional armies. Morley is a giant, which grants her immense physical strength. She is a Devil Fruit user, and her Oshi Oshi no Mi lets her shape the ground any way that she sees fit.
Lindbergh is a Mink, with an aptitude for creating scientific weapons. He can use Electro and also has access to Sulong transformation. Karasu ate the Susu Susu no Mi, a Logia-type Devil Fruit that gives him the power to control soot. In the Reverie, Morley, and Karasu were able to hold off Ryokugyu and Fujitora without any problems.
7 Rob Lucci
Rob Lucci is a member of CP0. Originally, he was in CP9, but he was kicked out by Spandam after being defeated by Luffy. The World Government didn't want Lucci's talent to go to waste, so he was promoted to CP0.
Lucci is an elite fighter who has mastered all forms of Rokushiki. He possesses the Neko Neko no Mi, Model: Leopard, which increases his physical abilities significantly. Lucci has also awakened his Devil Fruit, which further boosts his strength.
6 Ryokugyu
Ryokugyu was recruited by the Marines in the World Military Draft. He was appointed as an Admiral alongside Fujitora. Ryokugyu's silhouette was shown in the Reverie arc; his full appearance came toward the end of the Wano Country arc.
Ryokugyu ate the Mori Mori no Mi, which is a Logia-type Devil Fruit. It allows him to manipulate flora, giving him a lot of flexibility in a fight. Ryokugyu can use the vines to drain moisture from the bodies of his opponents. He utilizes Busoshoku Haki to protect the plants from being damaged by regular fire attacks.
5 Fujitora
Fujitora is one of the few Marines with a strong sense of morality. He made his debut in the Dressrosa arc, where he had minor tussles with several characters. As an Admiral, Fujitora is only below Akainu in terms of authority.
Fujitora possesses the Zushi Zushi no Mi, a Paramcia-type Devil Fruit that grants him control over gravitational forces.
By increasing the gravitational force over an area, Fujitora can create a massive hole in the ground. Furthermore, he can bring down meteors from the skies to cause widespread destruction. Fujitora can use Busoshoku and Kenbunshoku Haki; his control over the latter is extremely refined.
4 Sabo
Sabo is the chief of staff of the Revolutionary Army. He is the right-hand man of Monkey D. Dragon, making him the second-most powerful member of the Revolutionary Army. Sabo ate the Mera Mera no Mi, a Logia-type Devil Fruit that allows him to create and control fire.
Sabo is also adept at using Haki, which amplifies the power of his Ryusoken attacks. Sabo clashed with Fujitora during the Dressrosa arc and stalled him without suffering any injuries. It is important to remember that at the time, Sabo didn't have complete control over his Devil Fruit. He has likely become stronger since then.
3 Saint Figarland Garling
One of the biggest revelations in the Egghead arc was related to the Holy Knights of Marijoa. Monkey D. Dragon stated that the Holy Knights are extremely powerful individuals. The Holy Knights are the protectors of the Celestial Dragons, and they can overrule even the Marines in Marijoa.
Saint Figarland Garling is the commander of the Holy Knights, which automatically makes him their strongest member. He used to be the king of God Valley but likely gave up his role after the incident involving the Rocks Pirates. Saint Figarland Garling has the authority to execute a Celestial Dragon, something that is inconceivable to most people. He possesses a sword, but his skill remains to be seen.
2 Five Elders
The Five Elders, or Gorosei, are only below Imu in terms of authority and power. To protect Imu's secret, the Five Elders put up the charade of being the most authoritative figures in the World Government. Any order from the Five Elders is carried out by the Marines, Cipher Pols, and Holy Knights.
While talking to Cobra in the Empty Throne room, the Five Elders used their Devil Fruit powers for the very first time. It seems that all of them have Mythical Zoan-type Devil Fruits, which is not surprising as they are the rarest types of Devil Fruits. The Five Elders, along with Imu, were able to scare Sabo, which is a testament to their power.
1 Imu
Imu, of the Nerona family, is the true sovereign of the world. They sit atop the Empty Throne and pass orders to the Five Elders. Imu is immortal and probably possesses the strongest Devil Fruit in the entire world. When Cobra was in the room, Imu used their power to injure the king of Alabasta.
Considering Imu is the most important person in the World Government, it is safe to say that they probably have a Mythical Zoan-type Devil Fruit. Now that the manga is in its final arc, it won't be long before their true power is revealed to the readers.