Although Hydreigon are not true legendary pokemon, multi-headed dragons have long been the stuff of legends, and slaying one as impressive and world-changing an accomplishment as slaying a Giratina. The story in which one fell in love with a robot is no easier to accept than that the continents were formed from a slain Hydreigon's heads – except, of course, for the attestation in the Violet Book of a creature with a striking resemblance to that myth.
Iron Jugulis does not originate from a coupling between a Hydreigon and a machine, for the former has DNA and the latter lacks it, but this story and Iron Jugulis' true purpose may possess a common origin. Legends were told about Hydreigon because it was the most powerful thing in the sky that mortals were ever likely to encounter, and control of the sky has mattered in warfare since the day that first clever commander tied a note to their Pidgey's leg. Hydreigon must therefore have been a natural choice for mechanization, and it should be no surprise that Iron Jugulis' wings and necks were modified to create a faster and sleeker flier.
The very existence of the myth of a Hydreigon and a robot – described as an 'automaton' in the original text – suggests that whatever time paradox led to the Violet Book's creation happened more than once. Enthusiasts have scoured global mythology for other attestations of the future pokemon it describes; only in the case of the Swords of Justice and their machine counterparts, however, have they found anything remotely relevant. But it should not be forgotten that prehistory holds many more pokemon than appear in the Scarlet Book; and we can only hope that the same is true of our future.