How to transfer a Genymotion Desktop virtual device to another Computer?

Open VirtualBox on your source computer
Right-click on the device you want to transfer and select "Export to OCI..."
Make sure to select the Open Virtualization Format 1.0 format and export the device
On your target computer, open VirtualBox and select File > Import Appliance
Import the OVA file you exported earlier

The imported device should then appear in Genymotion Desktop GUI.