Here is the full list of all 12 Fret Nice achievements worth 200 gamerscore.
Clear the first level
Get all medals in any level
Have all 4 power-ups at the same time
Get 100% of all medals
Complete the game on Hard difficulty
Clear at least 3 levels with all 3 controller types
Get 10 enemies within the same bubble
Crush 10 skulls without touching the ground
Clear all levels using a guitar
Defeat 100 enemies using the Fire Boots
Revive another player 10 times in co-op
In single player, clear each standard level collecting less than 20 points