how do I defeat this pig?

The intended way is to pop that balloon to the bottom of him (either white or yellow) and hope that he flies out. To increase the chances of him flying out, use those fans to the bottom of the slingshot to ensure that he doesn’t get into the dead zone. It is also possible to strike that room with a ridiculously precise shot by grey by aiming her below that black hole thingy, activating her to the bottom-left of the lantern, and kicking KP into the fan above him, through the black hole, and out to the left side of the screen. Worked first time for me

Here’s a video of it done with the normal method: https://youtu.be/4uz6nh5WavE?t=184

And here’s a video of it done with that ridiculously precise method that I was chattin about: https://youtu.be/1_0DJTAJSV4