Here is the full list of all 19 Comit the Astrodian 2 achievements.
Collect 100 Yellow Stars
Collect 500 Yellow Stars
Collect 1000 Yellow Stars
Collect 5 Red Stars
Collect 25 Red Stars
Collect 50 Red Stars
Destroy 100 Enemies
Beat Planet Paradise
Beat Planet Aquatica
Beat Planet Mechanos
Beat Planet Shock
Beat Planet Party
Beat Planet Blizzcicle
Beat Planet Red
Beat Planet Dark
Beat Planet Starlight
Beat the Game
Unlocked Meta Comit
Defeat the True Final Boss