Transgenders say, since they are “women”, they should compete against women, and undress where girls undress.
We simply need to find a specific term and definition that distinguishes between the physical characteristics, which give rise to running separate sports programs.
If “woman” and “man” are now nebulous identities, then we just need leagues for “born with a penis” and “born with a vagina”. We can deal with the few cases of intersex people on a case-by-case basis.