Ok so if Vector is supposed to represent Beelzebub, then what are the other demons that you associate the Barian Emperors with?
ALRIGHT HERE'S WHERE THINGS GET TRICKY since with the other Emperors it's not nearly as clear what Prince of Hell theyre meant to represent as it is with Vector "Alien Beelzebub" Vector Zexal is. And it doesn't help that there isn't even a concrete list of the Seven Princes of Hell either, multiple authors have assembles their own version of the seven over the centuries! So we got a lot of different demons potentially on the field, and a little bit of It Could Be That Deep analysis has gotta be at the ready when considering the rest of Don Thousand's Finest. It's honestly a bit easier to try and maybe equate the remaining Emperors to one of the Seven Deadly Sins and try to work backwards to figure out their hypothetical demonology match from there (since I do very much think it's pretty clear the Barians are meant to parallel the sins on some level too because the Bible simply does not stop with Yugioh Zexal.)
The only other Emperor I feel fairly confident with is Nasch being tied to Leviathan, a pretty consistent member of the demonology 'royal' hierarchy and also, yknow, a fuckin water-associated sea monster! (and the first number we even see in the show is Shark's Leviathan Dragon, after all.) Leviathan's dead sin is Envy, which is maybe not the Most Shark-like, but still interesting to think about with him.
So that's Beelzebub for Vector and Leviathan for Shark. As for the others, I will posit some guesses:
Mizar: Most likely Lucifer for him... between his almost angelic type looks + having an association with dragons (as does Lucifer in the Bible) + Lucifer being the demon typically associated with pride it seems like it parallels him the best.
Girag: MAAAYBE MAMMON?? Demon who is kind of Just Some Guy but also associated with greed...since in his past life we know Girag would share the spoils of his conquests with the poor there could be some sort of wealth implied connection in there. Hmm...
Alito: Thinking maybe Satan [Prince of Wrath] for him.... his Barian form is even classic devil red which feels like a pretty deliberate choice.
Dumon and Marin/Merag: ok these two I have no real idea on. Marin could maybe be tied to Belphegor, who is sometimes described as taking on the appearance of a young woman??!? But idk. Dumon honestly almost has more in common with Furcas from the Lesser Key of Solomon than some of the more prominent demons. Hmm...
