Simulation is a necessary step to allow the experiment of new multi-vehicle scenarios. In this context, new tools are needed to test and validate the feasibility of the mission, the local and temporal behavior of the vehicles' controllers and the efficiency of the algorithms used. That's why we propose Thetis, a real-time multi-vehicles hybrid simulator for heterogeneous vehicles. This simulator allows Hardware In Loop (HIL) simulations including virtual sensors which allow to provide a representation of a virtual world, and including the support of communication devices. The architecture of this simulator is conceived so that it ensures a temporal decoupling between the virtual environment, the vehicles, sensors and communication simulators and, of course, the actual embedded controller which warrants us the temporal consistency of the results. Our contribution concerns the proposed simulator architecture. This architecture gathers all the important features required to simulate a flotilla including communications skills. It is designed to facilitate collaborative work between the different actors involved in this type of scenario. This paper presents the architecture and functionalities of Thetis and present some simulation results with the support of communications.