Latias @ Soul Dew
Trait: Levitate
EVs: 112 HP / 204 SAtk / 192 Spd
Timid Nature (+Spd, -Atk)
- Dragon Pulse
- Recover
- Hidden Power [Fire] / Grass Knot / Thunder
- Roar / Refresh / Toxic
This is a support Latias set I have been running and really enjoying. The EVs come from the DPP support set and ensure that Latias outspeeds Garchomp when it's not Choice Scarfed, survives two Water Spouts from Choice Specs Kyogre and is able to 2HKO support Groudon with Dragon Pulse. Adding more Speed EVs to ensure outspeeding Terrakion is definitely an option, but in my opinion not worth it on a support set, seeing as Terrakion is less problematic for it as for a Calm Mind set for example. Hidden Power [Fire] is amazing for nailing Forretress and Ferrothorn, who both like to come in against Latias to start laying down their entry hazards. I personally run Hidden Power [Fire] now and I've never looked back. This doesn't mean, however, that Grass Knot, Psyshock and Thunder aren't perfectly fine options for a secondary attacking option.
For the final slot I recommend either Roar or Refresh. Roar works amazingly in this entry hazard dominated metagame, especially seeing as Latias can easily force switches to rack up the damage done by Stealth Rock and Spikes. It's also very helpful against several Calm Mind Pokemon, who otherwise could be problematic to deal with. Examples are: Kyogre, Arceus-Fighting, Arceus-Grass and Manaphy. Refresh cures the ever dreaded poison which can be caused by users of the move Toxic, such as: Lugia, Ferrothorn, Forretress, Chansey/Blissey, Cresselia, Gastrodon, Gliscor and Heatran. It's also very helpful for when Latias gets paralyzed by Kyogre's Thunder and perhaps even when Chansey/Blissey uses Gravity in combination with Toxic Spikes, although this is very rare.
In conclusion I want to give Wish a mention, seeing as Latias is one of very few Pokemon viable in this metagame that actually has access to Wish (Alongside Chansey, Blissey and Jirachi). A Dragon Pulse - Wish - Protect/Recover - Thunder/Psyshock/Grass Knot/Toxic set could work for sure, I personally believe that after Wish got a mechanic change ever since Black & White were first introduced, this job is better left to Chansey or Blissey.
I encourage you all to try this Latias set out, I think it balances support and offense just about right, which in my opinion, is what Latias should do.