I once advocated 'meta characters'. Characters that have very specific transformations that the writer assumes are there. This is easier for writers to keep track.
For example I would create a 'base line character' which every scene should support. Imo something like a herm ausar that has dick, balls, vag, and tail.
A more elaborate scene can support for example a succubus character with horns, wings, multiple dicks and multiple vags, nipple genitalia and I am sure I forgot a lot more.
Then there are the special cases of taur and goo. They always need special scenes. Scenes that work for taurs likely don't work for other PCs.
I think it helps writers by saying: "If it works for the base line, the parser will make it work well enough for other PCs. If you don't know what to assume about the PC, assume they look like the base line."