A bi-level Stackelberg game model is established for coordinated trading among multiple virtual power plants and the dispatch of aggregated electric vehicles. At the upper level, trading prices are optimized to maximize the net profit of the virtual power plant operator. At the lower level, the operating cost of each virtual power plant is minimized by coordinating micro-turbines, energy storage, wind power, interruptible loads and aggregated electric vehicles. Electric vehicles are modeled only as time-varying connected resources in VPP4. Charging and discharging uncertainty is addressed by robust optimization, and the bi-level model is solved by Bayesian optimization. Case studies show that electric vehicle aggregation improves local flexibility, dynamic pricing promotes inter-VPP trading, and robust optimization enhances dispatch stability.