How do I defeat Octoroks?

You can reflect their pellets back at them in two ways:

  • With your sword: Do a vertical swipe at the projectile.
  • With your shield: Jab your Nunchuk forward just before the pellet hits for a counter-block.

Also, once you get the Slingshot from Bucha, you can shoot them (which stuns them), then run up and simply finish them with your sword.