Here goes
The DragonBall Z references were just way too much this time. I mean, sure Sonic does sonic wind in the games etc, but things like the fusion are just a plain rip off, and the whole gathering rings from all over the world reeked of spirit bomb. I mean, dude, you even traced wave animations from DragonBall Z.
That's not the worst thing though; the worst thing was how they good guys won. It pretty much went Nazo powers up, Sonic and Shadow fuse and power up, Nazo powers up, AND POWER UP AND POWER UP until for some reason, Nazo can't powerup anymore. It was just...terrible. You could have done something awesome and original, like the chaos emeralds scatter because they're being used by too many people and then they have to fight in their normal forms, or Sonic has to beat Nazo in a race to them or SOMETHING unexpected. I mean, at the end of the day it's just that they used the chaos emeralds over and over until someone lost. How is that exciting?
My final criticism I have to mention, is that the backgrounds are pretty bad. They seem like a complete after thought most of the time, the pencil tool really doesn't work with them, I find.
There were some fucking awesome bits though, mainly the part when Shadic hits Nazo, and then flies over to the mountain, then continues flying to Nazo. The overworld view was awesome. I also liked when Shadic flies down from space to the ground, and goes past all the clouds etc.
I also liked how you actually used Knuckles and Tails this time, rather than making them helpless side characters. Well done for that. Some of the voice manipulation was also well done, like "Shadic" etc.
I see you've put a lot of effort into this, but it does have too many noticeable flaws for me. A solid 7.