Since your friend seems to be into shonen but not mecha, you might want to try Berserk, Fist of The North Star, JoJo's Bizarre Adventure, Basilisk: The Kouga Ninja Scrolls, (maybe)Fate/Stay night, or (maybe)Excel Saga to start. If you want to try to broaden his horizons, Rozen Maiden, Gunslinger Girl, Gurren Langann or Elfen Leid might have enough action to keep him interested while exposing him to other genres.