Tough boss dude....
God okay for all of those having trouble beating the boss here's some tips you might be able to use
( the damage ratio is completely random so there's no telling if this will work everytime or not)
S.S. Sonic hits between 600-700 in his normal attacks
his Extra attacks hits between 1400-1500
Normal sonic hit between 200-220 in his normal attacks
The boss hits increase when you change into Super Sonic so when in super sonic he hits between 30-40's with mormal attack and his special move does 100-120 (okay here's the stradigy)
Turn into super sonic as soon as possibe and use ur extra attack. It should take a good begining chunk off his health if it hits 1500 or higher ur in business. Save the second extra attack for when he gets ready to knock u out of super sonic. If u do this properly (with alot of hope) he should have somewhere in 6500-6700 hp left. Now this is where your gonna need to pay attention to his attack pattern.
After u go back to normal sonic he will do that sword attack. take the hits and use ur normal att. he will use his normal att again than after ur turn he will use his special att keep repeating this until ur health falls in the 100's category. if he just used his special at to knock u there att him instead of healing. (he never uses special att twice in row) so than he'll use his swords on u. if they hit 20's on u att him one more time, if they hit 30's u can still att him. than after his att ur health should be between 60-70 on ur turn heal (it will fill ur health up completely, u can heal through the fight twice) after that his att patern will repeat and you do the same stuff over again(this guide doesnt work everytime but it should work most of time)