If you are well-familiar with the lore of the Tekken series, you will know that Kazuya won the very first King of Iron Fist Tournament, which should already make him the rightful choice for your own tournament run.
His main style is centered in Karate, but in fact, Kazuya can do so much more than that. His combos are very elaborate and require a lot of skill and practice. Probably the hardest thing to accomplish is to dash during combos, which is possible by forward dashing (f,F) and holding the F. After that, you can finish off any combo you like.
Below you can witness Kazuya’s devil form during his Rage Art (down/forward + left punch + right punch):