EIICHIRO Oda throws a big hint of how the Horsion is chosen

This post contains spoilers for one piece.

Summary

Imu chooses Gorosia members based on their origin from families who have united against the Great Kingdom. They should be capable of fighters.
Gorosei members are the former knights of God with the strong abilities of the devil and probably use the conqueror. They are at the Yongko level.
The knights of God, like Gorosia, have powerful abilities and known for their power. Imu must be a formidable force.

Gorose, also known as five elders, is the Pentad of the most important people around the world. They serve within the IMU, which gives them different roles. Gorosia obeys each Imu team and make sure they promptly perform the assigned tasks.

Because Imu's identity is a well-protected secret, they can't choose random people to become Horsem. Therefore, Imu must have a list of requirements that you need to fulfill before a person can be selected. While ODA did not clearly reveal the details, the author One Piece fell on the main hint of how the Horsion was chosen.

Showing a fan of One Piece, delighted with Luffy & Kizaru in episode 1127

“This will be the movie”: Fans of One Piece, delighted with Luffy & Kizaru in the episode 1127

The next episode “Lufffy and Kizar” will come out of everything to go out.

As imu chooses Hardei

One piece - five elders who bow to it when he sits on an empty throne -2

The main requirement for the choice of Gorosia member is that they probably came from one of the families who united against the Grand Kingdom. If they are connected to any of these countries, it is incredibly betrayed by the world government, which will make them more reliable.

Another condition is that a person should be a great fighter. All Gorosei members are at least the Yonko level, and you can even say they are higher than the level. The availability of weakness without the experience of combat will mean that they will not be able to protect Imu during danger. An experienced fighter will also be easier to obey Imu's orders. All Hardei is usually old, indicating that Imu expects them to gain sufficient experience and trust.

The strongest carefully selected imu

The easiest way to get the experience of the battle and the trust would be to join the knights of God. People who are in God's knights also share certain features with Horsi, such as regeneration and the ability to use the wheels that cause. In the Egghead Jaygarcia Saturn, the Circumstone used to call for backup. In the arc, Elbef Sherok did something like that when caused Killingham and Sommers.

Another thing that indicates that Hardei was former members of the knights of God is how Harling Figarland was chosen to replace Saturn. Harling Figarland has served a heavenly dragon for decades, and he was even declared his champion. Over time, Harling was transferred to the post of the Supreme Commander. When Saturn was unable to prevent the vegopon transfer, the imma somehow drained his life and made a new head of science and defense into Harling. This incident is more confirmed that the members of the knights of God are moving, and they become God or the Horsema.

How strong are the Hardery and the Knights of God?

Saturn faced with the vegopen and the straw

Gorose and God's knights can recover
They overcame the abilities

As mentioned, Gorose is at the same level as Yonko. It can be argued that they are stronger than pirates and they are not mistaken. Gorose has overcome the devil's skills of the fruits with which they can take over the entire fleet themselves. In addition, all Gorosei can probably use the conqueror hacking, and they seem to be extremely effective when using it. On the other hand, it means that the Figalland's Harling also has a conqueror's hack to continue the subject. When five elders were on Egged Island, there was a common chaos.

You dare to call me a man …? We are gods !! —Thow

No one was able to get against them, which is a great testimony to their skills. It should not be mentioned that their main purpose was to stop the broadcast, and therefore they were not fully focused on eliminating people on the island. Thus, it is safe to say that everything would be much worse if Horsya was concerned only by eliminating all living things. In addition, the straw hats wouldn't survive if Emet did not use the Khaki Jocky Boy to send four Harce.

The knights of God are not so far from Gorose. By this time, the knights of God have inflicted chaos in Elbef, without harming. Like Harde, they are armed with powerful devilish fruits and the ability to recover and cause others. With so many strong bases, one can only imagine what Imu should be.