What Psychic answered is Latios' best "mixed" set; however, Earthquake in this set is used to lure Heatran actually, and not as a physical attack Latios should use.
Latios @ Dragon Fang
EVs: 252 Atk / 4 SpA / 252 Speed
- Dragon Dance
- Draco Meteor
- Zen Headbutt
This is a set I crafted and started to use End-XY and Debut-ORAS. Now I stopped since Latias is my buddy better than Latios would be. However, when I used this set, this is how it worked:
- Draco Meteor anything and switch. Opponent will assume you're choiced. Save the Latios for end-game.
- Bring him. Draco Meteor. They'll have a fake sense of safety. If you force a switch, do Dragon Dance. Then proceed to eliminate everything with your physical attacks.
It wasn't easy to use but paid off when I could pull it. However, if you don't want to screw on EVs and don't like this set, Psychic's set is the best for a mixed Latios.