This actually makes perfect sense. Everytime I was beat by a Greninja I was using a relatively fast character and it was Shadow Sneak specifically that was beating me up.I have found that due to the mechanics of Shadow Sneak, Greninja tends to do well against characters that rely on speed. When you have Sheik dashing towards you to land some hits you roll the opposite direction and can Shadow Sneak into their direction. If that fails, you can just get them with the Counter.



















