Reverse Engineering and Static Analysis:

APKInspector: It is a powerful GUI tool for analysts to analyze Android applications.
APKTool: A tool for reverse engineering 3rd party, closed, binary Android apps. It can decode resources to nearly original form and rebuild them after making some modifications.
Dex2Jar: A tool for converting .dex files to .class files (zipped as jar).
JD-GUI: A tool for decompiling and analyzing Java code.

Dynamic analysis:

Drozer: Drozer allows you to search for security vulnerabilities in apps and devices by assuming the role of an app and interacting with the Dalvik VM, other apps' IPC endpoints and the underlying OS.

adb: android debug bridge. Connection process:
1. Run genymotion
2. Connect to virtual device: adb connect \<device IP\>
adb devices: list of attached devices.
adb install \<droxer-agent.apk\>: install drozer on device.
After installing Drozer, set the password in Drozer console and enable ssl.
adb forward tcp:31415 tcp:31415
drozer console connect