I've noticed that psychic is a bit lacking in the mix department, apart from Azelf, there aren't really any mix attackers. EXCEPT, mixtios, a set I've been running for some time, and it's brought me great success. People focus so strongly on Latios' immense SpA, that it's very usable Atk stat (Base 90) and great speed makes it a very viable user of Dragon Dance.
Latios @Dragon Fang
Trait: Levitate
EVs: 252 Atk | 4 SpA | 252 Spe
Naive Nature (+Spe, -SpD)
-Dragon Dance
-Earthquake
-Outrage
-Draco Meteor
It's 110 Speed stat allows it outspeed a crap ton of the unboosted metagame, and at +1, it outspeeds pretty much everything, bar Rock Polish Terrakion, Max Speed Venusaur, and random things like Choice scarf Jolteon.
In addition to this, you'll often find that Volcarona will either switch in on, or come in after a Draco Meteor, due to its decent special bulk. At -2 SpA, Volcarona generally has nothing to fear from Latios, even if it's bluffing choice and carries Surf. But the DD set, DD on the turn Volcarona no doubt Quiver Dances, then OHKO with Outrage. Tyranitar, also being normally being a hard counter to Latios can be 2HKOed with EQ after switching in on a Draco (regardless of spread, as if it focuses on one defense, its other loses out). Considering that unboosted Pursuit cannot OHKO Latios, what is once seen as a solid counter, is now only a check.
Scizor, however, is still a very solid counter to Latios, so as always, it needs to be taken out before Latios can do anything.