what do the electron configurations for all the group 18 noble gases have in common?

 they all have zero valency, they neither accept no donate electrons, they are said to be non-reactive,  they are called noble or inert gases.

 they are unlike group 1, 2 and 3 element who are metallic and can donate 1, 2 or 3 electrons respectively nor like group 5, 6 and 7 non-metals that can accept 3 ,2 or 1 electrons respectively to attain the stable state.