Okay. This truth is, 50 years ago this AO-Maru was created by Professor Gerald Robotnik and Black Doom after they they created Shadow. Philmac the AO-Maru is very powerful and most dangerous then Primus himself, but Professor Robotnik erase all of his memory, reprogram him to have kind heart just Maria and put him sleep. Feared that if he fall into the wrong hands it will be a disaster, so he send Philmac to somewhere that no one will fine him even Black Doom, to Neo-Top City where the original AO-Marus come from before they were destroyed by the Organization 13 & the Armada.
Thanks, but that's not all. In Team Robot In Harry Potter & The Prisoner of Azkaban, When Philmac was defeated by Primus someone gave him a demon serum when he was unconscious. with the demon serum combining with alien DNA it turn him into a AO-Maru hybrid.