Woah, woah, woah... I think you are jumping the gun here...
>Fighting all kings by himself...
It is just an illustration of two factions fighting the war...
Joyboy had Ancient Kingdom on his side and all Ancient Weapons belong to that side.
As you can see, even when WG got their hands on one of those weapons they are incapable of using it by themselves.
Joyboy was probably born during the war, it is unclear if he was even alive when it started.
They all are CoC users...
This was a no brainer the whole time since one of them has shown it.
As salty as always.
Just accept that Zoro does it all 100 times better than Luffy.