$d^2 s p^3 \rightarrow$ inner octahedral complex $\&$ diamagnetic.
$$
\left[\mathrm{Zn}\left(\mathrm{NH}_3\right)_6\right]^{2+} \longrightarrow s p^2 d^2
$$
hybridization (outer) and diamagnetic.
$\left[\mathrm{Cr}\left(\mathrm{NH}_3\right)_6\right]^{3+} \longrightarrow d^2 s p^3$ (inner) and
paramagnetic.
$\left[\mathrm{Ni}\left(\mathrm{NH}_3\right)_6\right]^{3+} \longrightarrow s p^3 p^2$ (outer) and
paramagnetic.
Related Theory
The main difference between inner and outer orbital complexes is that the hybridization of the atomic orbitals of the central metal atom of inner orbital complex involves inner shell $d$ orbitals whereas the hybridization of the atomic orbitals of the central metal atom of outer orbital complex involves outermost shell d orbitals.