Jet quenching in the hot, dense medium formed in Au+Au collisions leads to the suppression of high $p_T$ particles which can be studied with the measurement of the leading hadrons, like $\pi^0$. They can be used to investigate the mechanism of energy loss of partons in a QGP when varying the collision geometry. Asymmetric Cu+Au collisions provide a system with similar energy density but different collision geometry when compared to Au+Au, with the same number of nucleon-nucleon collisions. Furthermore, at RHIC we can study different highly asymmetric collisions, such as p+Au, d+Au and $^3$He+Au. The observation of collective behavior in these systems suggests the creation of a medium, but alternate explanations exist. The systematic study of the $\pi^0$ production could give us deeper understanding of the physics in these very asymmetric systems.\\
We present new measurements of $\pi^0$ with PHENIX in the asymmetric collisions at midrapidity $|\eta|<$0.35 with collision energy $\sqrt{s_{NN}}$=200 GeV.