Perhaps a little light.
I really liked it, but I imagine Zero's theme to be even heavier - possibly a cross between regular and melodic metal, maybe with deathy overtones - rather than the whole power metal thing you seem to have at the moment. Even though it's a cover, I'm sure you could do something cool with it. Still, it has a very nice 'vibe' and shows good musical talent. I'm giving it a 9/10.