Thread:Alexey de Greit/@comment-29933641-20180313155136/@comment-32295718-20180313164502

There are less types of Grimm then types of heartless, so just use all of the species of Grimm and chose the Heartless that are the most similar to the Grimm. For example, you could use the Large Bodies for the Ursas or Wyverns for the Nevermores or the Groundshaker for the Nuckelavee. The choice is yours.

And the internet says that the genral rule of thumb for determining an organs weight is "750 lbs per stop". I have no idea what a stop is, so this is likely not helpful at all.