Jikos - Pretty much every set that Latias does well is either a special sweeper or a tank...you might want to clarify what you mean by those terms.
The Latias sets worth using are Defensive/Offensive Calm Mind, Life Orb with 3 attacks and Recover, Choice Specs/Scarf, Dual Screens and Wish support.
supermarth64 - I'm fairly certain the answer is no.
Tyler - I'm not 100% sure on No Guard, but I think it was removed. Thunder and Blizzard still have 30% chances to hit through Protect in Rain and Hail respectively.
TempestJG - Theorymon is making statements about Pokemon, in particular about a specific pokemon or moveset, without backing it up with experience. It's usually based around calculations and performance in common situations (ie sweeper x 2HKOs everything in OU provided Stealth Rock and Sandstorm are up).