High data rates, large coverage area and reduce the effect of multipath fading are key points of researcher for wireless communication systems. These facilities are provided by MIMO systems. However, to implement and use multiple antennas are very difficult due to size, power, cost, and weight constraints. So, Virtual MIMO concept was introduced. In cooperative wireless networks, a virtual antenna array is created using several single antenna devices. Hence it is often the case that number of sources and number of relays cooperate to send their data to destination. For the cooperative systems, selection of appropriate relay node is of very important. This research works is focused towards the Fuzzy Logic based relay selection and power allocation (PA) using Gray Wolf Optimizer (GWO) algorithm in cooperative communication system.