I've got 13 out of 17 (though I should only have 11...). I'm missing Ambush, Brutus, Spotlight Finish, and Snowstorm, though the first two should be easy if I team up with my friend. As for the two I got illegitimately, I got Bauer one day while playing with Vegas (wtf?), and it was on the second of two songs that it said I got a 21-point match, even though I didn't get a 21-block match in either. I also seemed to get 30,000PPM, even though I've never scored that much. The strange thing with the 30,000PPM achievement is that I saw the pop-up telling me I unlocked the achievement twice, once after a song, and a second time while starting up the game.
I'd ask to have these two achievements removed from my stats, but I don't know how to go about doing that.
On a side note, I got all of the Ninja Mono achievements with Buckethead songs.
EDIT: Got two more achievements (Snowstorm and Brutus), bringing the total to 15/17 achievements, 13/17 legitimately. It was almost 14/17 legitimately, but I missed 30,000PPM by only 5,000 points on one song.
EDIT TWO: I finally got 30,000PPM legitimately, so I only need to get one more legitimately (Bauer), and the two others I haven't unlocked regardless.
EDIT THREE: I got the Bauer achievement legitimately now; I only need Ambush to go.
EDIT FOUR: I got my last achievement, Ambush, yesterday (12/22).