In Super Smash Bros Wii U (or Smash 4), it is a common strategy to 'tech.' This is when you press the shield button right before you hit the ground or wall of the stage, to avoid bouncing back up or just laying there.
In order to execute a tech correctly, you must time your button input correctly. There is a small window right before your character hits the stage that you can press the shield button. Does anyone know the length of this period, in frames?