Just faced a good Greninja, holy jesus; he can spam mini shurikens at you until you take an aerial approach, and he has superb jumps and combo attacks in the air to avoid that; kill potential's definetely a problem for him, but he can hydro pump ( up B ) while you're trying to recover back up and just blow you away from ever getting back on, provided you're not Kirby or Jigglypuff. His other special tools work great for his slipperiness aswell.
Been playing as Shulk against him, switching up stances to see which works well against his approach, but still struggling; any suggestions for the future?