The fight is pretty dumb. But.
Thing is I think it's less about you speeding up to catch Robotnik, and more about just not getting hit. The more frequently you are hit, the more you're pushed back which delays your approach(allowing you to score a hit).
The next thing is once you get into melee range of the Time Eater, his wrists will glow with a green aura briefly which signals that it's about to use a melee attack, if you don't fly up and avoid it you'll be pushed back and have to go back to dodging the debris and missiles and arms and stuff.
So the thing is you can't really go faster to catch up, you just can prevent yourself from going slower and falling behind.
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