Skills required to become an Android Developer are:
Knowledge of Android platform
Experience with Android SDK
Experience with Android framework, as well as offline storage, threading, and performance tuning.
Must be familiar with RESTful APIs to connect Android applications to back-end services.
Development experience with accelerometers, touch, gryoscopes, and additional sensors.
Experience with Android UI principles and best practices.
Knowledge of the open-source Android ecosystem and the available libraries.
Experience with cloud message APIs and usage of push notifications.