Why not make a "Creatures of Grimm" creation section just like the character creation? followed by the "approved Grimm" section, or a section called "The Grimm Encyclopedia", where the approved Grimm are stored with the following format which should cover all of the Characteristics.
Creatures Of Grimm
*= None EX: beowolf from Ruby Trailer
**= Light EX: "Nevermore"
***= Average EX: "normal" beowolf
****= Moderate EX: Ursa Major
*****= Heavy EX: Death Stalker