You would almost certainty need batteries warmed by nuclear decay.
The rest of the structure would also need to be warmed, again by a nuclear core of some sort.
Solar panels would be a waste of time.
You would need to give it an extremely powerful, yet low energy computer and sensors able to take readings and perform calculations quickly.
Even the most sophisticated technology would freeze and become unusable very quickly on Pluto.
There are also violent wind and ice storms that would damage the equipment, but that also brings up the point that you may want to have a relay satellite in orbit around the planet so that messages from the surface (which would be distorted by the storms) can be reprocessed and amplified before being directed to Earth.