Since that's the only thing in there, should we change the import in the .py file, too?

I mean, logically yes, but technically at runtime more gets imported there, just not things we intend to re-export.

I was being a bit conservative here and only changing stub behavior (especially since the stubs didn't pick up Subplot as being exported, when it should be)

I actually think __init__.py files (broadly) are good candidates for inlining type hints and just not having separate files: they are short, contain little to no actual function definitions, it's mostly imports and __all__ (which I'm also in favor of adding in more places)

Looking at __clear, I see also legend_ and title that aren't here; should they be added as well? (The former appears in axes.pyi on Axes)

I'd say those ones (and perhaps several of the existing attrs) should be made private (title there is already _[left|right]_title which are private, though the getters/setters are defined in _axes.py, not _base.py, for some reason, and not defined for secondary_axes, even though the attrs exist)

But I'll add them since they are by naming convention public (though I will also note that none of these attrs (aside from dataLim and viewLim) actually appear in the rendered docs, though several (trans[Axes,Scale,Limits,Data] come to mind) are referred to by examples, etc. Is that something we want to include in the rendered docs? cc @timhoffm, this is reminiscent of the discussions regarding plt.Axes/plt.Figure, but is different in that these are not imports and are instance attributes)

ax.title is used in several tests as well as the lifecycle tutorial and tight_layout_guide

axes.legend_ is used outside of the axes module only in backend/qt_editor/figureoptions.py as far as I can tell through quick greps (and never in documentation)