In the Additonal Comments of the Specs set mention Heatran, Ferrothorn, and Bronzong, as partners for the Specs set. Awesome offensive and defensive synergy, and all are able to provide SR and / or Spikes. Partners that can abuse a choice locked Pursuit from Tyranitar, or partners that can beat Tyranitar in general (as you can at least double switch at them when predicting the Ttar switch-in) should also be mentioned. Offensive SD Scizor, SD Terrakion, and SD Lucario are all great choices.
In general, bulky Steel-types that can set up hazards are some of Latios's best partners and should be mentioned in the AC of all sets, so please take care of it.
Finally, mention Weavile in checks and counters.
Part of the OU QC team, message
me for a check!