Quick Kill Strategies
 Early Bombs
This strategy only works if you manage to get bombs early, but is very efficient in defeating Kalle Demos in the fastest manner when executed.
Basically, you want to position Link so he's under the boss, and throw the bombs up into the boss. The bombs get stuck inside the boss, and the hit box of the explosion damages the boss. After five hits the boss dies.
 Forest Water
This newer strategy works on both Wind Waker and Wind Waker HD, and doesn't require getting anything earlier than the game intends on you getting, but requires Forest Water.
The setup for this strategy involves battling the boss as intended, throwing the Boomerang to cut the tentacles holding the boss in place down. The main difference is after the boss falls to the ground. At close range, what you want to do is pour the Forest Water onto the Boko Baba. If successful the boss will immediately go into its death cutscene, ending the battle in victory!
 Need Help?
Here is a handy guide on defeating Kalle Demos and other bosses from the Wind Waker.
Bosses of The Legend of Zelda: The Wind Waker