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