Cool team man!
So if you're running Scarf Magnezone, you're actually better off running
Choice Scarf Magneton. The Magnezone family is on of the few in the realm of Pokemon that actually loses speed when it evolves from Magneton to Magnezone. Your use of Magnezone as a Scarfer shows that speed is valued in the situation, and Magneton has a higher base speed. It has base 70 Speed instead of 60, which means it can outspeed Starmie and +1 Dragonite and +1 Gyarados.
I agree with Mr. Green's rate; the specially defensive spread he suggests for Skarmory helps take some pressure off of Gastrodon to wall Tornadus-T, who we all know is a top threat. It also helps it sponge special dragon-type attacks coming from the likes of Latios and Latias. While you do have Tyranitar for these threats a smart player can beat you 1 v 1 as you lack Crunch or any Atk EVs. Because of this the Lati@s player can stay in on Tyranitar and take the weak Pursuits, potentially setting up or KOing Tyranitar.
Gastrodon also desperately wants a
Sassy Nature with Earthquake over Earth Power solely for CM Jirachi. SubCM Jirachi in particular is gaining a lot of use in this metagame thanks to its astounding power in the Rain, the most common weather condition.
A final suggestion you could consider is trying
Shed Shell on Tyranitar. Dugtrio is so often found on opposing Weather teams and Tyranitar really is just a sitting duck waiting to be trapped. You do lose out on the only recovery Tyranitar has though, which would turn Lati@s into even bigger threats. But with Skarmory's new EV spread I believe this is worth it. Sandslash
needs the Sand up to be effective and if you lose Tyranitar you're pretty much also losing Sandslash.
Good Luck!
Sets:
...
Magneton @ Choice Scarf
Trait: Magnet Pull
EVs: 4 HP / 252 SAtk / 252 Spd
Timid Nature
- Volt Switch
- Thunderbolt
- Hidden Power [Fire]
- Flash Cannon