So there's a Ninja Spike, but wouldn't it be awesome if there was a Pirate Spike also? Well, there is one!
Unlike the Ninja Spike this is not done with a throw, nor is it named after a Kirby hat. Instead, it derives its name from Tetra's Ship on the Pirate Ship stage. The Pirate Spike is not limited to any particular character - you can do it to anyone - but only on the Pirate Ship stage.
In order to perform a 'Pirate Spike' all you have to do is Inhale a victim and drop into the water on the left side of the ship. Make sure you are facing toward the ship when you fall into the water because your Inhale will 'water-cancel' and the opponent will break free and float into the ship's hull where they get spiked.
The most efficient way of getting a Pirate Spike on someone is a ledge-hopped Inhale. As you fall back past the ledge drift over to the hull. If your distancing is correct your opponent will be spiked and Kirby will not get hit.
Yarrrrr!