that's a fair point. it's possible that Imu can only possess characters that are ageless like Gunko and Gorosei. though all HKs seem to have some kind of connection to Imu because of regeneration, but I think it's possible the Gorosei and Gunko are the only ones who can do stuff like performing the summonings.
i guess it was literally just the slave hunt... still hoping he'll get a cool moment worthy of hype.
it can still happen a bum vs a bum makes the most sense
i guess it was literally just the slave hunt... still hoping he'll get a cool moment worthy of hype.
it can still happen a bum vs a bum makes the most sense
So, in order to become a Gorosei, you have to give Imu part of your Soul. Same thing with whatever Gunko's position is as Imu's attendant: this fits well, since it would be 6 people, a number associated with Demonology.
If the Celestial Dragons knew reincarnation was real, it would make a lot of sense for most of them to not want to share their Soul with Imu, and be trapped in the same age/body forever.
I think this is why Mars had the dialogue he did when he looked at Vegapunk's Brain in Punk Records:


Mars almost seemed... whimsical, towards the idea of death, here.
Imu only being able to possess people who have shared their Soul with Imu makes a lot of sense.
It is possible that Imu can take over anyone who has a Mark of the Abyss, too, though.