Multi-robot systems have many useful real world applications including disaster management, exploration and surveying. Formation control is critical in these contexts as the success of groups often depend on the ability to generate and maintain particular formation shapes. It is also important that a multi-robot system can evaluate and select appropriate alternative formations when an ideal formation cannot be upheld, particularly in dynamic real world scenarios. A distributed formation selection mechanism that addresses these issues by enabling groups of unmanned ground vehicles to autonomously select, scale and morph formation shapes when navigating through dynamic environments is presented in this paper. Experiments on non-holonomic ground moving robots demonstrate the suitability of the proposed technology.