Currently, the wiki for solo states the following:
A single character with unnamed pet or object characters. Images involving animals or creatures with a character tag (talking or otherwise) alongside another character should not be tagged solo.
This doesn't all that clear to me, especially the part about character tags (since people are often reluctant to create this).
Based on (the frankly quite old) forum #138283, it seems that the intention is to separate "generic" animals and creatures from "specific" ones (which may have a chartag, have some canon (or fan-made) story behind it, or act somewhat like people in the post). I'm not really against it, but I would propose a change to the wiki to make this clearer (assuming I interpeted this intent correctly, which is why I'm making this post). So something like:
A single character with non-specific animals or creatures. Images involving specific animals or creatures (like ones with a character tag, talking or otherwise) alongside another character should not be tagged solo.
The change is kind of minimal but it's 2:30 in the morning so if anyone has other suggestions that'd be great too.
I also think that the "can be solo" examples section is kind of confusing, and it might be better to just have these examples part of the "yes solo" and maybe a "no solo" section.