I'd say: universally Demonic Co-Pilot and some Recovery/Toughness stuff, with a catch of Holy Stuff. They all seem to have Recovery, probably even Supernatural, but the lesser ones may not have Toughness -- Kincaid takes down the 'Obsidian Statue' Denarian with one shot, for example. That's all I'd say is *really* universal.
Then most have Beast Change, and Human Form affecting their other powers, which can vary a lot (possibilities: Speed or Strength powers, Breath Weapon, Claws (maybe Venomous), Hulking Size (for Ursiel for example), maybe even better Toughness, whatever.) [They may not ALL have this shapechange -- Nicodemus doesn't seem to.]
Those that can use magic also get Sponsored Magic (Hellfire).
The layout varies a lot by individual Denarian, I think -- they're basically unique creatures. Some have most of their power locked up in their combat-shapes, like Ursiel; others, like Tessa and Rosanna, are more magically than physically powerful. Also, their total power level varies way more, IMO, than Our World really suggests (it tends to way over-stat them, in my mind) -- I'd put only Nicodemus at 'plot device' level, and I doubt most of them are really operating at the -15 to -20 Refresh big leagues. (Ursiel probably is, Tessa probably is.)
I might stat some out in a thread...