Find the number of ligands winch be have predominantly as $\mathrm{\pi }$-donor ligand (as well as non-classical legend)

${\mathrm{C}}_2{\mathrm{H}}_4,{\mathrm{C}}_6{\mathrm{H}}_6,{\mathrm{NO}}^{+},\mathrm{NO},{\mathrm{CO}}_4{\mathrm{NH}}_3,{\mathrm{NH}}_2^{-},{\mathrm{H}}_2\mathrm{O},{\mathrm{OH}}^{-}$