Changing focus a bit, I fell that, with these new drops, Latias rather enjoys the following set:
Latias: 72hp/184spa/252speed
Timid Nature. Life Orb/Leftovers/Dragonium-Z/???
-Hidden Power Fire
-Roost
-Thunderbolt
-Draco Meteor
Draco Meteor is STAB and Roost is so Latias can properly wall things. The other moves are here for the sake of giving Latias good coverage against most of it's checks/counters: HP Fire roasts Scizor and Bisharp, and Thunderbolt can not only beat up Mantine but, after Stealth Rock damage, 2HKO Togekiss and Assault Vest Azumarill. Case in point:
184 SpA Life Orb Latias Thunderbolt vs. 240 HP / 16 SpD Assault Vest Azumarill: 172-203 (42.8 - 50.6%) -- 95.7% chance to 2HKO after Stealth Rock
184 SpA Life Orb Latias Thunderbolt vs. 252 HP / 0 SpD Togekiss: 190-226 (50.8 - 60.4%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
The EVs are the same as last gen's offensive defog, and I don't see much reason to change them, since Latias can survive a surprising amount of stuff with them, but still, full offensive sets are also possible.
Latias: 72hp/184spa/252speed
Timid Nature. Life Orb/Leftovers/Dragonium-Z/???
-Hidden Power Fire
-Roost
-Thunderbolt
-Draco Meteor
Draco Meteor is STAB and Roost is so Latias can properly wall things. The other moves are here for the sake of giving Latias good coverage against most of it's checks/counters: HP Fire roasts Scizor and Bisharp, and Thunderbolt can not only beat up Mantine but, after Stealth Rock damage, 2HKO Togekiss and Assault Vest Azumarill. Case in point:
184 SpA Life Orb Latias Thunderbolt vs. 240 HP / 16 SpD Assault Vest Azumarill: 172-203 (42.8 - 50.6%) -- 95.7% chance to 2HKO after Stealth Rock
184 SpA Life Orb Latias Thunderbolt vs. 252 HP / 0 SpD Togekiss: 190-226 (50.8 - 60.4%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery
The EVs are the same as last gen's offensive defog, and I don't see much reason to change them, since Latias can survive a surprising amount of stuff with them, but still, full offensive sets are also possible.