The Sixaxis Compatibility Checker is a free download. If you have a generic controller you should definitely use this to see if the controller works or not.
From what I can tell, the Sixaxis software should work with any recent Android device, like a Nexus 7 for example.
As to whether it has to be an authentic PS/3 DualShock Controller - I can't answer that, since I don't have any generic controllers to test with. The description does mention some generic controllers that work, and of course you could wing the developer a note asking about whichever controller you have.
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