Yes, it exists. Latios can be a roaming Pokemon in Emerald and Soul Silver, obtained in Pewter City as a gift Pokemon in Heart Gold, and found in the Dreamyard in Black 2. When you first encounter/recieve Latios, its IVs and Nature are determined, so it is very unlikely but possible that a Timid, 6 IV Latios was actually captured.
If it is from Hoenn, Unova or Kanto it is legit and can be used in Online Battles. If from Johto or Kalos it is hacked and can't be used.
Source: Above Link & Experience