This work proposes a decentralized super twisting control scheme for group formation and trajectory tracking of multi-agent system networks with a fixed topology. Each agent dynamics is represented by a single-input single-output nonlinear system in its normal form and the information required by each controller is the output of the others agents. It is proved that output consensus and trajectory tracking can be achieved with the proposed super twisting control. Moreover, the state space representation of the agents dynamics is not restricted to be of the same dimension, as usually assumed in the literature. The stability of the controlled system is proved using a Lyapunov function and a simulation example is provided in order to illustrate the application of the proposed control.