Seriously BAMF
Well, I don't think I can add much that hasen't been said already. I would like to say that Shadow is a serious BAMF in this one though (bad-ass mother f*cker) I'm glad you went back to the older style of explosions too, from Metal Slug(?) I really like trying to figure out where to get some of the pieces for this, like Mecha Sonic's huge fireball (the sun) the sprites you used for the Axem Rangers (Mega Man Battle Network) and others I'm sure were too well placed for me to catch. The only thing I worry about is you'll get burned out before you finish the series, but that's just a personal phobia. Great work!