Well, hopefully the voters for the suspect test will be announced soon, and I hope to be one of them. This topic is pretty much dying, so I thought I'd give my opinion on each of them.
Latias: Definitely gonna be OU. It has already been shown to not be overpowering in OU, and in this test was far overshadowed by Latios. Those different stats really hurt. Also, way to easily revenged by Weavile, Scizor and Tyranitar.
Manaphy: Once again, definitely OU. It may just be me, but in my experience Manaphy was very underwhelming. I didn't really play much in Manaphy testing, but as it was voted uber I assumedit would be more powerful than it is... The only time when Manaphy is really a threat is in the rain, and the abundance of T-tar stops the rain. I don't think Manaphy would be overpowered in OU at all.
Garchomp: Garchomp could go either way, I don't really know. The SD Yache set is very dangerous, but the presence of scizor could help with that. Also, Latias will be a very easy check to Garchomp, so long as sand veil doesn't ruin it. Sand veil+Brightpowder is very dangerous, and causes a lot of misses, not helped by the fact that Tyranitar is one of the most used pokémon right now. I'd assume their might be an increase in Machamp usage, with No guard.
Skymin: Another one I'm unsure of. We already have seen how deadly pokémon with serene grace can be coughjirachicough and considering Skymins large special attack and STAB on Air Slash it is very deadly. Not to mention Seed Flare, 80% chance of a sp.def drop, which can eliminate it's possible counters. However, it is fairly frail, and Mamoswine and Weavile can easily revenge it. Still unsure of which way it will be going.
Latios: This is the only one that I definitely think will be uber. 110 speed, 130 sp.atk, and access to the best STAB, I definitely think this would overcentralize OU. Basically every team would need to run a Blissey. If that's not overcentralisation I dunno what is.
Well, this is just my opinion, and I'm sure all of you have your own opinions, that differ vastly from mine. I look forward to hearing them.