I notice a pretty bad weakness to fighting types, since ferrothorn, heatran, stoutland and tyranitar will all easily die from a close combat of terrakion or a mach punch from breloom. While Landorus and latias fix this problem a bit, they are still not enough to stop completely fighting types. Without changing too much on this team i would say to try out a double booster landorus-t. The moveset is Stone edge / Earthquake / Rock polish / Sword dance, with a spread consisting of EVs: 252 Atk / 72 Def / 184 Spd with an Adamant Nature. The evs are to outspeed scarf latios after a rock polish and the rest of the evs are in def to get a random bulk. Landorus-t have a few advantages over landorus, the main one is intimidate, that will help you a bit against fighting types since you can lower their atk, as well as being able to setup more easily on phisical attackers. Its a very underrated pokemon in my opinion and it works similarly to landorus, but it can also act as a better wall breaker because it has also sword dance, which can be more important if you will face defensive teams.
With landorus-t, i think the only things you will be weaker against are Gliscor and skarmory. If you do the change of Cbtar over your current set, you dont have anything to fear against skarmory; if you dont want to use cbtar, i think its worth considering a mixed set for tyranitar with fire blast and ice beam to catch those things in predict, probably instead of stone edge and pursuit, since you can pursuit things with stoutland as well. Those moves are also good because stoutland will appreciate the absence of gliscor and skarm, as well as others steel types such as ferrothorn, that will almost die with a fire blast. Anyway, i see a bad weakness to focus blast users as well, mainly gengar and sash alakazam, so i think its worth a try a chople berry in your tyranitar over leftovers, which is in my opinion an almost useless item on sp def tar. With chople berry you will be able to eat a focus blast and strike back a ko, it can also help against focus blast thundurus, just in case they run it.
Lastly, i would put a different spread on Stoutland. I know its good the added power with adamant, but with this spread you will be outspeeded and probably koed by 3 common scarfed pokemon, terrakion, keldeo and latios. If you use this spread EVs: 80 HP / 252 Atk / 176 Spd with a jolly nature you will be able to outspeed and kill those stuff. In my opinion the main point should be to outspeed things with stoutland rather than hit hard, so thats why i wanna change it.
Thats it, gl with your team!