Guitar Hero 5

This is pretty simple, and it is pretty easy, if you know how to get this achievement. This also isn't about playing the song, it's about how well you can play it in carreer mode.

These are the songs and challenges as to how I achieved it:

Scars on Broadway - They Say (Expert Drums, 200 snare hits)
Beck - Gamma Ray (Expert Bass, 340 upstrums)
Coldplay - In My Place (Expert Guitar, whammy 30 seconds worth of sustains)
Garbage - Only Happy When It Rains (Easy Vocals, 75% filled of Star Power Meter)

However, this isn't the easiest way, all though it is the fastest. These gigs listed below are the easiest, as I got diamond on all on my first go on expert. They will also unlock a few more achievements with these along the way:

Scars on Broadway - They Say (Drums, 345 snares for Diamond) - Located in The 13th Rail
Brand New - Sowing Season (Yeah) (Bass, 475 upstrums for Diamond) - This song is slower than Gamma Ray, making it easier to get your upstrums. Located in Club Boson
Rags to Rich's Guitars (Guitar, 175000 points for Diamond) - Pick Song 2, but make sure you alt-strum on the triples. You'll not only get Representative, but also No Mistakes Allowed with the alt-struming. Located in Club Boson
Public Enemy - Bring the Noise 20XX (Vocals, 75 phrases for Diamond) - While this may not seem easy, here's why: you don't have to do a single thing. If you just turn the song right, turn the volume up enough, and put the mic in front of a speaker, you'll get a perfect on this. This will get you Iron Lungs. Also, if you decided to plug in a guitar and play on medium, you'll get The Streak. You're also guarenteed your No Mistakes allowed if you haven't achieved it already. But you have to make sure that the vocalist is on your main profile, and the guitar is on guest, or you won't get any of them. Located in Neon Oasis.

For people like me--who have difficulty with playing on Hard or Expert--I thought I'd share how I just got this (all in Career).

Scars on Broadway, "They Say": 13th Rail (first gig)
medium drums (200 snare hits)... I was able to ignore the bass pedal, and everything else that wasn't yellow or orange, except the red-yellow pairs (yellow is the snare).

Gorillaz, "Feel Good Inc.": 13th Rail (first gig)
easy vocals (4x or more multiplier for 30 sec.)... not too much variation in the vocals, I actually got platinum on this (60 sec.) Humming works fine, in fact I would suggest it for the trickier passages (which still aren't all that hard) :-)

Darker My Love, "Blue Day": Club Boson (second gig)
medium bass (score 15000+ pts. in star power)... I made it comfortably even though I didn't have a 8x multiplier for every activated star power.

John Mellencamp, "Hurts So Good": Club Boson (second gig)
medium guitar (whammy sustains for at least 15 sec.)

This last one (guitar) was the only one in which I wasn't sure that I would reach the Gold Challenge level before the end of the song... I had tried Coldplay (listed in the previous solution) on medium and not made it, probably because I didn't try whammying the shorter sustains, and it needed 30 seconds. I also tried Beastie Boys "Gratitude" (hit 15 tap sections) on medium, but missed it by a couple.

I had to whammy quite a few short sustains in the Mellencamp song in order to make it to the Gold level, and my wrist was about to break :-( So, if you're a medium-level guitar player, it's really a toss-up (at least it was for me).

If you've gotten as far as the Sideshow (the third gig) in Career, you might try Wild Cherry's "Play that Funky Music," since that one is maintaining star power (4x or more for 50 sec.) instead of whammying sustains. That's the next one I would've tried if I hadn't got Gold on the Mellencamp song.

Hope this helps you, my fellow medium peeps. Good luck!