Eva 00 - Prototype Model
Unit 00 was the first Evangelion unit to be produced and is piloted by the first child, Rei Ayanami. In order for it to be useful in close quarter battles with the angels, NERV had to upgrade it shortly after the destruction of the 8th Angel: Sandalphon (the volcano). Previously, this Eva was used to protect Unit 01 from a high power energy beam shot by the 5th Angel: Ramiel. It was severely damaged after this encounter and required much repair work, including a new paint job (from orange to blue). This unit, like Unit 01, has run amok on a couple of occasions. The reason for this was thought to have been because of mental instability in Rei, however, it is later determined to be from the Eva itself after it goes haywire without Rei inside. Inside Unit 00 is the soul of Naoko Akagi, Ritsuko's mother. It was probably placed into the Eva after she committed suicide in front of her creation, the MAGI, after finding out about Gendo's betrayal of love towards her from the first copy of Rei Ayanami. This explains why when Unit 00 goes haywire it tries to kill Gendou and the first copy of Rei.
Eva 01 - Test Model
Eva Unit 01 is piloted by Shinji Ikari, the Third Children. EVA-01 is the Evangelion that has been in the most battles and has the highest success rate. This is because of either its pilot's natural talent, or because of the fact that the Eva has an extremely powerful being within. This unit is also the most prone to go haywire, often in impossible situations. This is not necessarily bad because more than once the Eva has destroyed the Angel successfully, and left Shinji alive to tell of it. This Eva is a mixture of Adam AND Lilith's DNA, explaining why it is so powerful. On at least three seperate occasions the Eva has operated without power from the cable or batteries. After it was first created, the Eva began to create / grow it's own energy core like the ones of the Angels. This may have been known to be happening by the more powerful members of the NERV organisation. This core enabled it to operate without the need for the umbilical cable or batteries, however it rarely did so, either of it's own, or of NERV's will. It only ever did so when it's pilot's life was in danger. After attaining awarness during it's battle with the 14th Angel: Zeruel, it defeated the Angel and consumed it to absorb the Angels power into itself. The soul contained in Unit 01's core is that of Shinji's mother, Yui Ikari. It is this soul within it because she was killed when she tried to synchronize with Unit 00. The existence of her soul is the reason why Shinji has many visions of his mother while in Unit 01's entry plug, and why in the very first episode the Eva protected Shinji from falling debris while not activated.
Eva 02- Production Model
EVA Unit 02 is the first production model Eva to be built, and therefore is the model upon which all future Evas are to be built. It is piloted by the second child Asuka Langley, and is the only Evangelion to have battled in extreme conditions. Underwater with the 6th Angel: Gaghiel, and 17 hundred meters down inside a volcano with the 8th Angel: Sandalphon. The Eva also makes use of a progressive lance, as opposed to the progressive knife (although it can use that also). Also, it is the only Eva which has to make use of settings in 2 languages, being that its pilot Sohryu Askua Langley, is bilingual (Japanese, German). Unit 02's core was built from the soul of Kyoko Zeppelin Sohryu, Asuka's mother, after her synchronisation accident and her subsequent suicide. Because of the stability of the model, it is probably not the best in combat and relies almost completely on Asuka's piloting ability.
