This is not a reaction with change in oxidation states.
Here from `Pb^(2+)` and `PO_4^(3-)` it forms `Pb_3(PO_4)_2` precipitate. So only that will take part in the net ionic reaction. All others are cancel out.
So the net ionic equation will be;
`3Pb^(2+)_(aq)+2PO_4^(3-)_(aq) rarr Pb_3(PO_4)_2_(s)`