In that case, Tyranitar is better without it's Mega Stone and better than Mega Gyarados in Ubers, as well as both choices being outclasses by Mega Salamence as Dragon Dance Sweepers. :P
Tbh, if you want an Ubers team that can keep up with the metagame, you need to lose all of your Pokémon on your team currently except Marshadow. Sorry if this sounds harsh, but competitive battling involves using what is viable, and ignoring preferences that bring no competitive value (like using favorites that are unlivable, refusing to accept the current metagame, etc.). :P