Instructions
Hold down the "Z" button to target Dark Link. This will keep him squarely in your focus no matter where he moves.
Hold your shield up to thwart Dark Link's attacks.
Walk slowly toward Dark Link. He will back up to keep space between you. Eventually, you will back him into a corner where he will keep doing back flips. This opens him up for attack.
Use a weapon such as the Megaton Hammer or Biggoron's Sword to dispatch this foe while he's trapped in the corner.