After some more sketching around, I decided to just give them all six limbs. They're not Earth creatures anyway, so why not? I'm making it official. They can have four arms and two legs, two arms and four legs, or (in a few cases who won't show up officially for a while yet) two arms, two legs, and a pair of wings.

Most of the four-legged ones have the "chair" arrangement like Patch there in the upper left, but not necessarily; Gimble's four legs are arranged radially, since her waist can swivel freely anyway and they're all left-right symmetric. As always, her feet can come together to form a conical shape that allows her to spin her lower half like a top.