Nice sun team you have here, anyway I have some advice to give you so let's go with the rate!
First of all, your team has a big weakness to Rock Polish Landorus. After a Rock Polish, it can 6-0'd you easily and also without boost in Speed you haven't switch into it. To solve this weak, I suggest you to use Bulky Life Orb Latias, replacing Volcarona.
The other pokčmon are very important for your team, otherwise Volcarona can be replaced without any problem, you have already Venusaur to take advantage of sun. Then, on Ninetales, I'd change Substitute into Roar
. Substitute isn't a very good move on Ninetales because it has to stay alive long to keep up the sun and lose HP due to Substitute is quite bad. Roar otherwise can be useful against many setupper like Volcarona, Dragonite and so on. Finally, I suggest you to use Thundebolt, replacing Thunder on Starmie
. Thunder has only accuracy 50% when sun is up and that's really bad, Thunderbolt otherwise has always accuracy 100% so I think it's fine.
Good luck, hope I helped!
Here's the set you should use:
Latias (F) @ Life Orb
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature (+Spd, -Atk)
- Draco Meteor
- Hidden Power [Fire]