No. 25: Sparkle Buster
Throughout the island where the game takes place, there are machines scattered about in various levels of decay. The same can be said for facilities, which depending on how deep they are, look dilapidated or brand new. Thanks to their protective paneling, Sparkle Busters are always brand new no matter where they're installed, even in the side of a cliff. Invincible while closed, you must attack them while they're opening or shooting at you. They come in two distinct varieties: A four shot rapid burst, and a single shot spread. Normally, they only open if you're close enough but like all machines, they will react violently if alerted of a threat by a Bun.
Cocoas are the same way. They're machines too, after all.
If I had to put an estimate on it, Sparkle Busters are probably the most common machine.
Oh, and since you asked, I haven't made a whole lot of headway in the music field yet.