Here is the full list of all 27 We Sing Pop trophies - there are 10 bronze, 10 silver, 6 gold and 1 platinum.
Played in Group Battle at least 10 times
Played Versus mode at least 30 times
Played Versus mode at least 20 times
Sing 1 song at least 50 times
Played Single player mode on Expert at least 10 times
Sing all songs on Expert
Sing 20 songs on Expert
Played We Sing mode at least 10 times
Played Pass the Mic at least 10 times
Sung atleast 10 songs with the instrumental track option
Sing in Expert mode for the first time
Play Pass the Mic for the first time
Played Versus mode at least 10 times
Play Versus for the first time
Score over 50000
Score over 25000
Sing your first instrumental song
Play We Sing for the first time
End a song with less than 10000 points
Sing your first song
Unlocked all trophies in We Sing
Sing your first karaoke song
Score over 25000 in 15 songs
Sing every song on the disc
Played Karaoke mode at least 10 times
Score over 50000 in all songs
Score over 90000