I only watched the trailers and did a few speedy wiki-walks, but that looks both super awesome and doable within the constraints of the DFRPG system.
The Grimms would just be bricks. Building blocks, maybe Pack Instincts in some cases.
Hunters/Huntresses might merit some building blocks just to accurately show how strong/fast/tough Aura makes them. I'd give Yang Supernatural or even Mythic Strength, for example, and I'd definitely give Ruby Mythic Speed. Definitely some stunts regarding high Weapons/Guns/Athletics.
The various weapons could be represented as Natural Weaponry, or IoP's if you feel that's more appropriate. Ruby, for example, would either have Ranged Potent Natural Weaponry (Crescent Rose, with Weapons), or Crescent Rose as an IoP that carried a stunt that let her wield it as a gun with Weapons.
The Semblances could probably be handled via Incite Effect or Channeling/Internal Foci.
EDIT: Watched the whole thing. It is really good. I never really got into Oum/Rooster Teeth's stuff, but that was cool. I feel that most of my assessments here are accurate.
