While the EMP looks good on paper, it would not be very effective in reality. The problem with EMPs is that you can't control what gets turned off. We could very well doom ourselves if it is not used properly.
What could work, however, is some kind of jamming signal. If we stop the robots from communicating with one another, they will be comparatively easy to kill. Another way is to attack their stronghold at night. Why at night, you may ask? Because they will inevitably have some kind of night vision technology. Night vision works by sending out infa-red light, which is invisible to the naked eye, but can be picked up by ordinary devices. With large infa-red flood lights, it is entirely possible to render their night vision useless, at which point they could be easily taken out with normal weaponry.
