Powers & Abilities How come Oden

[Sasaki Kojirō]

That was the result of the collision between Kaidou and Oden 24 years ago...
Their fight only happened 4 years later.
While the black rays aren't a solid indication of Adcoc use as Katakuri and Luffy emanated as well...

If I had to speculate here they are using Acoc.

 

[Dickie D. Dick]

Oden always has conqueror's Haki since early childhood.
Luffy and Zoro learn ACoC the moment they realise it's possible so I assume Oden didn't knew he could do it before he met Roger

 

[Boiroy]

I think if Enma touches Sanji's D, it'll awaken his Okama Haki as well.