The reason why klaus needed Elena's blood to make hybrids is because of the curse his mother placed on him. Esther made it so that he needed the blood of the doppelganger to complete the hybrids transition knowing that in order to create them elena would have to die, she used it as a fail safe. If he had not been cursed then his blood would be used to complete the transition just as Hope's is
Okay now I get it thanks