Power source for Arduino uno, sparkfun usb shield and adafruit motor shield
Its a very bad idea to power everything from the same battery source. Most motors, especially ESP, generate large current spikes, rather than draw a small current throught. AA batteries are not designed for this. 

You can get away with using AA batteries for micro-controllers, shields. However, keep motors on a sweater power supply. There are batteries for specific motor types, and these will typically have a high current rating. Of course, without a circuit diagram, I cannot go into details. I'll update my answer when you do.