Well what is a primal without worshipers? The Kojin worshiped the divine relics or kami. Thoradin became King Thoradin from prayers of ishguardians. Phoenix same thing. I am sure if there isn't aether crystals in close proximity certain primals can draw aether from their surroundings to compensate. The only limiter with susano was he had to have 3 relics in order to be summoned. He had everything a normal primal well as much normal as you could call certain ones required for summoning. Base materials prayers and aether.