Board Thread:Theories and Speculation/@comment-27002073-20160406173133/@comment-9782468-20160406215956

Kakashi can use wind release because he is listed as a user, even though the manga/anime don't show him using it.

Basically, he can copy any technique of Wind Release as long as he is actually skilled enough to use it. But since wind release is a cutting element and he already uses lightning for cutting power, he doesn't use it much. I'd say the best he could copy is high B-rank to low A-rank techniques; most S-rank techniques require you have an affinity for it.