https://www.adafruit.com/products/1404Also how what spots in the Arduino would the wires go in?
Also what is the difference between a continous servo and just a regular servo.
I assume by boxing robot you mean it continuously "punches" whatever's placed in front of it. If that's the case I recommend you use a simple dc motor attached to a crankshaft mechanism. You can get gearbox kits to create these types of things rather easily.
Servos need an external power supply similar to below.