Here is the full list of all 27 Bloo Kid 2 achievements.
Get all 360 stars
Finish the game on "Nightmare" difficutly
Beat the World 5 Boss without taking damage
Jump on 15 enemies in a row
Jump on 10 enemies in a row
Get 300 stars in total
Finish the Boss-Rush mode
Beat the World 4 Boss without taking damage
Finish the game on "Hard" difficutly
Beat the game in Time-Attack mode
Finish the game on "Normal" difficutly
Get 250 stars in total
Beat the World 1 Boss without taking damage
Beat the World 3 Boss without taking damage
Get 225 stars in total
Get 200 stars in total
Finish the game on "Easy" difficutly
Get 175 stars in total
Get 150 stars in total
Get 125 stars in total
Get 100 stars in total
Beat the World 2 Boss without taking damage
Get 75 stars in total
Get 50 stars in total
Get 25 stars in total
Jump on 5 enemies in a row
Jump on 3 enemies in a row