It's ok
Not the best, I like the voicing though. Sonic sounds a bit southern.
It woulda been raw if shadow could transform into superform from some unexpected side effect, like knuckles was cursed. Like that ancient beast should have blasted shadow with his final breath and shadow should have absorbed the beam to be super shadow and shadow is just waiting for the right moment to surprise everybody with his new power...oh well I'm not the script writer.
Fight scene was pretty cool though. I think you spelled seelkadoom wrong...