Here is the full list of all 30 Karaoke achievements worth 400 gamerscore. It takes around 25-30 hours to unlock all of the achievements on Xbox 360.
Do a gig with a DJ in the backup band
Do a gig with a keyboard in the backup band
Sing 5 Favorite songs back to back
Welcome to the top!
Do a gig with a chorus in the backup band
Earn 10,000 or more Fans in 1 session
Capacity limit? What capacity limit?
Added a song via Smart Glass
Sing the same song twice in a row
Do a gig with a drum set in the backup band
Do a gig with a guitar in the backup band
Do a gig with a bass in the backup band
Aim for the top!
Sing 50 songs
Your Fans are waiting for you...
Turn up the heat with your poses!
So many songs in your repertoire!
Congratulations on going the distance!
Even your Fans can't do this!
Congratulations on your debut!
Your Fans are copying you!
Sing 10 Free Songs
Earn the Over Capacity Bonus on a large size stage
Earn 15,000 or more Fans with one song
Register 100 songs in History
Reach level 30
Reach level 50
Become the Legend!
Use 30,000 Moola all at once when leveling up
Use a total of 500,000 Moola