Adding Hieratic Dragon King of Atum and Gaia Dragon in your extra deck instead some synchros or this second leviair would be nice, and then you could replace Adreus with Volcasaurus, since he will kill the opponent AND deal damage, and then you could still overlay Gaia Dragon on it and attack, Atum to be honest is just way to usefull in Chaos Dragons to be forgotten, having 3 MST will sure help more than droping some traps here and there, because due to the lack of trap in any chaos dragons deck, your opponent will mostly likely have his MST's on his hand, just waiting you set a card to use it, since they don't have anything else to do with it, just leave they with their dead draw mst then, backrow can hurt Chaos Dragons way too much.
About the side, I'd change basically every card on it, just some ideas: Maxx "C", System Down, Mind Crush, Deck Devastation Virus, Malevolent Catastrphe and Dust Tornado.