Magnezone can't do a thing to the Latis, you dolts. That's like saying Magnezone can take on Celebi. Like Celebi, the Lati twins resist Tbolt and have too much SpDef while lacking a 4x weakness necessary for HP Ice to have any real killing power. What is Magnezone going to do, try to Metal Sound and get two-shot through its resistance in the process?
it almost seems too powerful to bother testing but you have to realize that with stuff like weavile tar garchomp specsmence being whored, psychic dragon is pretty much the worst typing right now.
Dragon still has a good set of resistances and the fact remains it's arguably the best offensive typing due to lack of resists and the amazing power of the new Dragon moves (revampoed Outrage and Draco Meteor). They're still immune to arguably the most prevalent physical attack, Earthquake, and they outspeed and OHKO every one of their "threats" but Weavile (faster) and T-Tar (can't OHKO because of the lame-o Sandstorm buff).
Latias is also a fantastic support unit, but that didn't stop us from deciding to unban Celebi and Jirachi late in Advance times. ;/
Unfortunately, I have to somewhat agree with Jibaku. They're not exactly Mewtwo and we've already given the other "lesser ubers" a chance to be used in standard play. But if you think Salamence and friends are bad enough as it is, wait until you start battling Salamence+ and see how bad they are. There is little doubt to me that they would be "proven" too good for OU still.
The thing about "testing" is, especially in a tournament setting (like we were once going to do for Wobbuffet in Smogon Tournaments, what shoddy is doing with Speed Deoxys, etc.), is that the pokémon being tested is going to be used more than ever and going to be prepared for more than ever over the "test" period. The hype of testing, let alone the actual power of, the Lati twins is going to implore virtually everyone to use at least one. On that same token, most people are going to be extremely prepared for them, packing all sorts of weird T-Tar sets or relying on Weavile to revenge kill them every single time more so than normal. It's not as true a representation of their usage OR power as it could be, though it's still a little better than mere theory.
And yeah, keep telling us their oh-so-common weaknesses. "Celebi has SEVEN weaknesses, not uber! Ho-oh is 4x weak to SR, we should unban it!" The list of Bug users is basically just 2-3 pokemon and Gengar/Mismagius aren't exactly a ton of Ghost users. Not enough learns Sucker Punch and few things actually carry Dark Pulse/Crunch. Pursuit is strong, but everyone knows the 3-5 pokémon that typically use it and it won't hurt non-STAB anyway. Dragon weakness is pretty "meh" since they already kill too much at neutral power and Lati@s outspeeds other Dragons anyway. Ice is their only "big" weakness that a large variety of pokémon can take advantage of, but their defenses are too strong to be phased by most non-STAB Ice attacks (and Weavile already takes advantage of their Dark weakness).
Taking garchomp as an example, it may not be able to switch into a dragon attack but with prediction, it can certainly switch in and scare lati@s off with scarf outrage. Perhaps prediction may not be the best example as it's liable to debate.
Using "prediction" as a justification for other pokemon winning is retarded. The opponent could just as well predict you're switching to Garchomp that turn and blow you away with Draco Meteor. Oops!
As for Blissey, Salamence is more scared than Lati@s in general. A surprise CB set instead of today's more common Specs set may force Blissey to switch once (with half its health gone), but Salamence is also OHKOed by its Ice Beam and most be weary anyway. Lati@s doesn't really give a crap. Also, though not so much a CBer, Latios can play a DD set fairly well.