This achievement is related to the story,
When you enter the fight the first thing you should do is climb the tower, once at the top you can climb the boss.
When you have become super sonic the boss will launch rockets at you, wait for them with RT+LT and make a counter by pressing X. the rockets will hit the enemy and when you get close he will try to attack you, counter again, this will allow you to attack with X and decrease its life.
When he has half his life left he will start to throw some pink circles at you, in addition to the rockets, follow the same technique as before but this time when you are in front of he, he will attack twice so you must parry once, release the buttons and quickly make parry again.
Then, he will launch rockets towards you, you will see a big red circle and a white circle coming out of Sonic, when the white circle aligns with the red one you must press X, repeat the strategy until you defeat him.