Fusion of memory, processing and power components enables creating autonomous and monolithically-integrated dust-sized computers for ubiquitous computing. However, this effort is limited by contradictory ion dynamics and performance variability of each component. Here we report an all-in-one dual-ion device that integrates memory, processing and power functionalities. By electrically modulating ion species (Li⁺ and O²⁻) and amounts participating in the electrochemistry, the complete memristor modes (including analog, volatile digital and nonvolatile digital types) and on-chip power modes are created on demand in this device. Because of their distinct properties, the roles of Li⁺ and O²⁻ are easily distinguished and modulated by electrical operation for meeting the customized demand of each mode. Moreover, the homogeneous migration of Li⁺ ensures high uniformity of the Li⁺-based modes. The oxygen vacancy-based conductive filaments are finely defined by mechanical deformation through electrically controlling ion intercalation/deintercalation, thus guaranteeing high uniformity of the O²⁻-based modes. Both neuromorphic and logic in-memory computing are well demonstrated based on this all-in-one device.