The bond order and magnetic behavior of $O_2^{-2}$ ion are, respectively:

According to mot the electronic configuration of $O_2^{-2}$ ion is $\sigma 1s^2{\sigma }^{*}1s^2\sigma 2s^2{\sigma }^{*}2s^2\sigma 2p_z^2\pi 2p_x^2=\pi 2p_y^2{\pi }^{*}2p_x^2={\pi }^{*}2p^{2}y$

Bond order $=\frac{10-8}{2}=1$

It is also exhibit diamagnetic character due to no  unpaired electrons