I am not quite sure what you are asking, but I will say that you cannot evolve Nidoking and I will assume you are referring to Nidorino.
If I understand correctly, I will advise you that when a Poke evolves, its base stats will change. Here are Vulpix base stats:
HP 38, Atk 41, Def 40, SAtk 50, SDef 65, Spd 65, TOTAL 299
So you can see, Vulpix basically sucks as a Poke, not even getting past 300. Now, when it evolves into Ninetales its base stats change:
HP 73, Atk 76, Def 75, SAtk 81, SDef 100, Spd 100, TOTAL 505
Quite a jump in total base stats for Ninetales, in fact, even though it still is not a great Poke, it is in the top-60 when it comes to total base stats.
So, to hopefully answer your question, a Poke's stats will change when it evolves. Sometimes drastically.