Here is the full list of all 12 Meteos Wars achievements worth 200 gamerscore.
Unlock 20 planets for use
Unlock 10 planets for use
Play Attack Mode 20 times
Clear Mission Mode on Hard
Obtain 20 accessories
Launch 10,000 Meteos
Clear the screen 10 times
Use Geolyte 5 times
Clear Mission Mode on Normal
Obtain 10 accessories
Use Planet Impact 10 times
Clear Mission Mode on Easy