Do not be fooled by Latias's one year stint in OU. With Soul Dew attached, she is one of the most useful and versatile Pokemon in the Ubers tier, being able to check a huge number of dangerous threats, most notably Kyogre, while threatening to sweep at a moment's notice. Latias is also a brilliant support Pokemon, being able to pass Wish to teammates or set up screens to assist in a sweep. There is a place for Latias on any Ubers team and she will always perform her job well. She may not carry as much raw firepower as her brother Latios, but what she lacks in strength, she more than makes up for in bulk.
Latias steps forth from ADV into the treacherous grounds of the DPP Ubers. In the faces of Kyogre and Palkia, she stands in their way from completely ripping apart an Uber team. With her incredible hold item, Soul Dew, Palkia's Life Orb-boosted Spacial Rend also fails to OHKO. Using her Speed, she can threaten an OHKO on Palkia with Dragon Pulse before Palkia delivers a finishing blow (watch out for Choice Scarf variants). As for Kyogre, she stands without fear as its Ice Beam only does approximately 48% maximum, allowing Latias to Calm Mind and then Grass Knot or Thunder Kyogre into oblivion. With the help of Recover or Roost, Latias restores her health back into usability, and thus shines again in the battlefield, ready to take something else down. If the user is satisfied with only one offensive move, Refresh rids her of annoying status conditions like Toxic that malevolent beasts such as Fighting Arceus and Blissey enjoy inflicting on Latias, and the paralysis she might face when trying to switch into Kyogre's or Palkia's Thunder. Although Safeguard cannot stop any status she switches in on, it supports her team and keeps her safe for five turns so it is a decent alternative to Refresh. Latias can also make decent use of Substitute, although these variants of Latias are rare, and generally you will want to run the other suggested moves.Team Options & Additional Comments >>>
With her massive Special Defense, Latias can set up both Reflect and Light Screen with little trouble against many Pokemon in the Ubers environment. After setup, she can then sacrifice herself to pass this long-lasting protection to a much more dangerous threat such as Rock Polish Groudon, Rayquaza, Swords Dance Lucario, and Dragon Dance Salamence, to name a few. This Latias is usually best used mid- to late-game, when the recipient has already done significant damage to the opposing team but is unable to continue. Healing Wish gives it a "second chance" at sweeping, allowing the recipient to re-enter the battle at full health and free of any status ailment that it might have received during its first sweep attempt.
Reflect, Light Screen, and Healing Wish are obviously the crux of the set. The last slot is up to the user. Dragon Pulse allows Latias to deal damage and not be completely crippled by Taunt. Wish can be used if one wants to give the recipient a relatively safe switch in without sacrificing Latias in the process. Recover allows Latias to heal herself, allowing her to switch in repeatedly and set up screens throughout the game.Team Options & Additional Comments >>>
Roar allows Latias to phaze other Calm Minders trying to set up on her, such as Blissey and Arceus. Psycho Shift allows Latias to transfer status inflicted on her to the opponent, but as an anti-status move, it pales in comparison to Refresh and Safeguard. Hidden Power Fire and Dragon Pulse are unresisted by anything but Heatran, and will help Latias fend off those nasty Steels such as Metagross, Scizor and Forretress. However, Latias will lose the ability to beat Calm Mind / Rest Kyogre one on one. Psychic allows Latias to hurt Fighting Arceus. Finally, Draco Meteor is always available as an option if one wants to score some KOs where Dragon Pulse cannot, but it should generally be left to Latios, where he can use his higher Special Attack to score an instant OHKO on Mewtwo. Don't bother with Ice Beam—it fails to OHKO Groudon so one might as well use Dragon Pulse for the better coverage in the Uber metagame.
Latias is fairly adept at setting up a Light Screen with her massive Special Defense, allowing her to take special attacks like they're banana peels flung at her. Reflect is also an option, but her significantly lower Defense does not help with that. Lugia sets up Reflect better thanks to its much higher Defense. Healing Wish is quite gimmicky, as most of the time, sacrificing Latias is not worth it. Finally, Latias learns Charm, but Reflect is generally superior to it because the opponent could switch out of Charm, and the fact that Charm fails to touch Metagross thanks to Clear Body.
Trick is viable, allowing Latias to become a revenge killer of sorts with Choice Scarf, which is especially helpful against common threats like Dragon Dance Rayquaza. Blissey will detest Choice Scarf, which could well open a sweep for the likes of Kyogre easier. However, Latias won't like being without Soul Dew, and often enough Latios is slightly better at drawing in Blissey.
Checks and Counters
If Blissey has Toxic, she will always beat Latias without Safeguard, Refresh, or Psycho Shift. Even if she has Safeguard, Icy Wind can allow Blissey to get in a Toxic before Latias can refresh the Safeguard after it expires the first time. Thunder Wave Blissey can be annoying, as being fully paralyzed can spell your doom if they also have Seismic Toss. Tyranitar and its massive Special Defense will allow it to easily switch into Latias and beat her down with a Choice Banded Crunch. Even a Soul Dew boosted Grass Knot is incapable of 2HKOing Tyranitar (assuming that he is carrying Special Defense EVs). If Latias is not packing Thunder or Hidden Power Fire, Scizor can switch in and deal massive damage with U-turn, or punish a fleeing Latias with Pursuit.
Metagross is a great check thanks to resistance to Dragon Pulse, Grass Knot, and Ice Beam, meaning it really only has to worry about Thunder and Hidden Power Fire. It has a chance to OHKO Latias with a Choice Band Meteor Mash (guaranteed after Stealth Rock damage), and a Choice Band Pursuit will do even more on the switch. Dark / Bug Arceus can Calm Mind alongside Latias and eventually beat her down with a super effective Judgment. Ghost Arceus takes less than 50% from an unboosted Dragon Pulse and 2HKOs back with Shadow Claw. Steel Arceus will resist a lot of Latias's attacks, much in the same way Metagross does. Registeel's massive Special Defense allows it to take anything but Thunder and Hidden Power Fire (unless the weather is favorable for Registeel), and beat Latias with Ice Punch.
As for the revenge killing, Deoxys-A and its high Attack will OHKO Latias with Choice Band Ice Punch. Additionally, Choice Scarf Heracross can Megahorn Latias before she does anything. The move Knock Off really hurts Latias, as Soul Dew is her key to success. However, it should be not much of a worry, as the only notable user of Knock Off is Deoxys-D, who is quite uncommon.