There is a very high likelihood that the ability to do permanent damage to the gorosei is tied to laugh tale. Why?
Imu has been in power for hundreds of years. Since the void century and the defeat of joyboy, no person has been able to seriously challenge Imu's rule. The gorosei live in mariejois and don't take part in every day battles. This job is undertaken by the marines and the shichibukai. That is what the balance of powers represented.
Marines and Shichibukai vs yonko
The gorosei are outside this balance.
The gorosei essentially are to current Luffy what Kaido and BM were to pre-yonko Luffy.
Kaido and BM were untouched for decades.
Similarly, the gorosei have been untouched for centuries.
Hence it doesn't make sense for the secret to harming them to be some random ass thing anyone can use. Luffy is a yonko with advanced haki and awakening and he still can't damage them. If these tools don't let you harm the gorosei, tools that are already very rare in the OP world, then the secret to harming the gorosei is probably some of the most exclusive powers in the series.
Which is why I am guessing it is likely tied to laugh tale.
The last person we know for a fact could harm them was Joyboy. Hence laugh tale likely holds the secret to being able to damage them. This is why the WG is so scared of the One Piece being discovered. In addition to learning the true history of the world, someone who visits laugh tale could also know the weakness of Imu and the Gorosei.
My guess is that Rayleigh was probably the one who, using the clues from what he learned in Laugh Tale, discovered the method of damaging the immortals. The other characters who have this skill are probably tied to Rayleigh. Crocus, Scopper, Seagull, Sunbell, and Shanks are all likely candidates. Another one I would mention is Dragon. Dragon is leading the revolution against the WG, it wouldn't make sense to me for Rayleigh or the other Roger pirates not to give him this information.
In any case, that's probably it. There's no reason for random ass top tier characters to magically have the ability to bypass immortality, when they have never faced this power in their life. Kaido, BM, Mihawk, the admirals, it doesn't make sense for them to have the magic bullet to this uber hax ability just by chance. The WG has existed for centuries without any serious rivals. Random characters having the ability to hurt the gorosei basically undermines the journey of Roger and Luffy. Why is finding the One Piece even important if any top tier could theoretically challenge the rulers of the WG?
No. Luffy, the SHs, and their allies are special for a reason. They are the chosen ones who will bring down the WG. The other top tiers are tbh irrelevant.
Imu has been in power for hundreds of years. Since the void century and the defeat of joyboy, no person has been able to seriously challenge Imu's rule. The gorosei live in mariejois and don't take part in every day battles. This job is undertaken by the marines and the shichibukai. That is what the balance of powers represented.
Marines and Shichibukai vs yonko
The gorosei are outside this balance.
The gorosei essentially are to current Luffy what Kaido and BM were to pre-yonko Luffy.
Kaido and BM were untouched for decades.
Similarly, the gorosei have been untouched for centuries.
Hence it doesn't make sense for the secret to harming them to be some random ass thing anyone can use. Luffy is a yonko with advanced haki and awakening and he still can't damage them. If these tools don't let you harm the gorosei, tools that are already very rare in the OP world, then the secret to harming the gorosei is probably some of the most exclusive powers in the series.
Which is why I am guessing it is likely tied to laugh tale.
The last person we know for a fact could harm them was Joyboy. Hence laugh tale likely holds the secret to being able to damage them. This is why the WG is so scared of the One Piece being discovered. In addition to learning the true history of the world, someone who visits laugh tale could also know the weakness of Imu and the Gorosei.
My guess is that Rayleigh was probably the one who, using the clues from what he learned in Laugh Tale, discovered the method of damaging the immortals. The other characters who have this skill are probably tied to Rayleigh. Crocus, Scopper, Seagull, Sunbell, and Shanks are all likely candidates. Another one I would mention is Dragon. Dragon is leading the revolution against the WG, it wouldn't make sense to me for Rayleigh or the other Roger pirates not to give him this information.
In any case, that's probably it. There's no reason for random ass top tier characters to magically have the ability to bypass immortality, when they have never faced this power in their life. Kaido, BM, Mihawk, the admirals, it doesn't make sense for them to have the magic bullet to this uber hax ability just by chance. The WG has existed for centuries without any serious rivals. Random characters having the ability to hurt the gorosei basically undermines the journey of Roger and Luffy. Why is finding the One Piece even important if any top tier could theoretically challenge the rulers of the WG?
No. Luffy, the SHs, and their allies are special for a reason. They are the chosen ones who will bring down the WG. The other top tiers are tbh irrelevant.