  Following our earlier work we establish kinematic endpoint relations for
baryon decays using the Wigner-Eckart theorem and apply them to $\frac{1}{2}
\to \frac{1}{2}$ and $\frac{1}{2} \to \frac{3}{2}$ baryon transitions. We
provide angular distributions at the kinematic endpoint which hold for the
generic $d=6$ model-independent effective Hamiltonian. Moreover, we explicitly
verify the endpoint relations using an explicit form factor parametrisation and
clarify constraints on helicity based form factors to evidence endpoint
relations. Our results provide guidance for phenomenological parameterisations,
consistency checks for theory computations and experiment. Results are
applicable to ongoing and future new physics searches at LHCb, BES III and
Belle II with rare semileptonic-, dineutrino-and charged-modes, which include
$\Lambda_b \to \Lambda^{(*)} \ell \ell, \Lambda_b \to \Lambda^{(*)} \nu \nu$,
$\Omega_b \to \Omega \ell \ell$, $\Lambda_c \to p \ell \ell$, $\Sigma \to p
\ell \ell$ and $\Lambda_b \to \Lambda_c^{(*)} \ell \nu$
