I think if it is a serious fight Shikamaru would win because he has to protect people or he is depended on. If it was a match that could be avoided and was unecessary i would say Shino would win. Also i think Shikamaru brings the fullest potential of his Shadow Copy no matter the situation he seems to make it beneficial towards himself, Shino would put up a good fight ,but i don't think he would win.