I've found between using your shield at the proper times when one is getting ready to explode, then the dodge feature to lunge out of an exploding area right before they go off, and using the invincibility shield from the Seaphynx battle sprite, those three combinations tend to keep you out of harms way for the most part. Depending what depth you are at will also change the toughness. If you use the dread venom striker (or similar sword), PK will drop 2 candies at a time, since the attack has a double hit, using this means you only have to hit him 3 times, instead of 5, (to get the 5 candy drops before defeating him) and then you can use the warmaster rocket hammer to finish him off swiftly.
I've found between using your shield at the proper times when one is getting ready to explode, then the dodge feature to lunge out of an exploding area right before they go off, and using the invincibility shield from the Seaphynx battle sprite, those three combinations tend to keep you out of harms way for the most part. Depending what depth you are at will also change the toughness. If you use the dread venom striker (or similar sword), PK will drop 2 candies at a time, since the attack has a double hit, using this means you only have to hit him 3 times, instead of 5, (to get the 5 candy drops before defeating him) and then you can use the warmaster rocket hammer to finish him off swiftly.