The humanoid mechs that combat the Angels and keep them from getting to lilith so they dont use her to destory mankind
EVA's were engineered to deal with the global threat of the Angels. As such they have been specifically designed to counter the Angels energy wavelengths more specifically their A.T. fields. A.T. fields are invisible sheilds and what make Angels so difficult to damage due to its level of strength surrounding the Angel. However EVAs' produce their own AT fields causing destructive interface with the Angels AT field thus neutralizing it. The reason EVAs' can generate AT fields is because the EVAs' were created using the same forbidden technology that created the Angels. In fact beneath the EVA's metal armor exist an entirely organic organism. Meaning that EVAs' are just in fact Angels that have been bread to help mankind against the angels. The EVA's has restrictors beneath their armor designed to control them from going out of control but that alone is not enough for EVA unit 01 because this is not just an EVA it's an EVA with a soul inside of it in fact the soul belongs to the pilots mother. IT has been said that the soul of the mother of the pilot has been used for better user interaction with the EVA and the pilot.