Latias with Soul Dew is an absolute beast. I like this set:
Latias @ Soul Dew
Not sure what to put for the EVs yet..
Timid Nature (+Spe, -Atk)
-Dragon Pulse
-Substitute
-Calm Mind
-Recover
With it, you can beat Ferrothorn one-on-one, out stalling all of it's Gyro Balls. I usually haven't found a real need for another attacking option in my time playing DW Ubers.