After three years, I finally came around to finding the rest of this story!! So here it goes!!
After Sonic's noble sacrifice to his friend Shadow, four years later there's a blue comet that crashes to Mobius that's got everyone in a quick race to investigate and take possession of what this comet holds!
What can I say, Shadow759 from Youtube was all my inspiration! (Who can't admit he's just super freakin awesome!?)
Sonic adventure 2 battle: What if Sonic died and Shadow lived???