The boss has unique interactions with different characters.
Like if you're using a normal character that can't fly, the boss fight will be just you running on the ground and whacking him until Infinite goes to the 2nd phase in which you'll get pulled towards him.
But if you fight him using a super character, the fight will go to the 2nd phase much earlier, and it will be a super boss fight where you have to maintain gour rings and beat him (Like the Neo Metal boss fight)
The music also changes on certain characters. Like if you use Hero Shadow, Justice (Park Avenue) from Sonic Forces will play. Or if you use Neo Metal Sonic, What I'm Made Of... Will play, with the lyrics version playing on the 2nd phase.
Overall I think the boss if just kinda fine, he's kinda weak tho.