which god tier is most likely to be able to go into a Night Guy (8 Gates) like state and which one is most likely to have something similar to Susanoo?

Night Guy may be a Doom Thing, not quite sure about the Class- Perhaps a Bard? A Maid? Whichever case, the 8 Gates fits into the “High energy output but unsustainable and often self-sacrificial” aspect of Doom. As for a Susanoo, I feel something Heart or Hope-based could work. A Knight perhaps to Wield it, albeit a Page may work as well.