I figured I would rate this since I happen to see it all the time now. Quite honestly, I fail to see the hype, you are incredibly weak to Rotom, Azumarill breaks through you quite easily, and if you let it in, KS Aegis does some work. Thats actually not hard considering your win condition is Genesect. Mega Venusaur is also a problem. From what it looks like, you quite simply try and sweep with Shift Gear Genesect. Thats cool and all, but a lot of people actually give the SpA boost, so they dont eat a stronger U-Turn, and because Rock Polish isnt nearly as good as it was last gen. You use Azumarill and Mega Chomp to break through walls, which is nice until you realize they can be walled by common walls like Rotom or Skarmory. Your team also does NOT want to face Thunderus I. Nothing on your team wants to take on a focus blast/ Thunder Wave/ HP Ice/ Thunderbolt variant, one of the more common movesets out there.
First off it just amazes me how weak you are to Rotom-w. especially with all the hype surrounding this team. Nothing wants to eat a WoW. Nothing. ChestoResto variants even get past Gliscor, who is there to toxic it, only is hit extremely hard by hydro pump. And I have to be honest, that seems like the weak link here. I recommend Trevenant so you can beat up on Rotom, Azumarill, and Thunderus, as with Natural Cure you hard counter Rotom and can Leech Seed to heal up or switch to a teammate for psuedo passing. A specially defensive set is preferred, I'll let you come up with the EVs, as i dont want to bc its fking 4 o clock here. A moveset of Horn Leech/Leech Seed/ Will-o-Wisp/ Shadow Sneak should do you well, or you can run Sub in the last alot if you feel like it. Gliscor doesnt seem to do much except Toxic things, and thats great and all, but the metagame took a huge shift towards switching, so in the long run burn is actually more beneficial, as it is in the short run too.
There is absolutely no reason to run roar on Tyranitar. What are trying to stop from setting up on you? Lucario? Terrakion? You would be better off running Pursuit or Rock Slide to smack around Thunderus and Charizard. Speaking of which, I would also run Chople Berry as it lets you eat a focus blast from something and KO back.
Lastly, I dont see the need for SpecsTom. Choiced items can be a great liability in a fast paced meta such as this one, and you can trick yes, but its only asking for a Mega Evolution to come in and set up. I would switch that to Defensive Rotom. This gives you a second Talonflame check, as well as a hard counter to Mega Pinsir. Something you desperately need. The ability to switch mves is a boon, and you dont need a tricker/stall breaker because you have Mega Garchomp, who manhandles stall teams. Im too tired to add any sets, but have a Merry Christmas, i hope I helped with your team!