Electric vehicle (EV) is the most prevalent distributed flexibility resource that are currently available, and EV clusters show advantages in providing ancillary services. However, significant heterogeneity is observed among EV consumers regarding charging demands and acceptance of controlled charging. To address this challenge, a color-coded pricing mechanism is proposed for EV aggregator participation in energy-reserve markets, designed to balance diverse consumer requirements with flexibility utilization potential. Through the provision of multi-tier charging probability options and corresponding price packages, EV consumers are guided to participate voluntarily, enabling differentiated charging behavior management. A framework is established for EV aggregator participation in energy-reserve markets, where a bi-level optimization model is formulated to simultaneously maximize aggregator profits and minimize consumer charging costs. The solution strategy is developed based on the momentum gradient descent method. Case studies demonstrate that the proposed mechanism not only enhances economic benefits for both the aggregator and consumers, but also effectively facilitates aggregator participation in reserve markets while improving responsiveness to system regulation requirements.