In my opinion it's neither, ashura probably didn't use any bijuu remember how hagoromo had the floating truth seeking balls too? I think you just need massive senjutsu to utilize the truth seeking balls. The chakra could be melded into the beast you see juust like how susano is a spiritual manifestation of uchiha power, the avatar is a manifestation of physical raw energy. It makes sense susano is a spiritual warrior while that beast is a physical realm (temporal) beast, man vs beast kind of makes sense.