Latias->OU (it's easily walled and trapped)
Manaphy->Uber (a monster offensively, also very bulky defensively)
Garchomp->Uber (scarfchomp is the best revenge killer, bulky and fast. When you trap Latias, Yachechomp is gg. If the opponent hasn't got ice shard or fast ice scarfers, habanchomp is gg.)
Garchomp:Uber. I feel Garchomp still needs to be uber because it outruns many of the Ice Pokemon that are capable of OHKOing it. It even has a set that runs Yache Berry so it takes two ice type attacks to knock it out. The Choice Scarf variety is also quite dangerous. It has access to a pretty versatile movepool both physical and special. Being able to be used in so many ways makes it too powerful for the OU tier. Factor in the ability Sand Veil due to Tyranitar and or Hippodon being used with it and there will be a fair number of hax misses that can cause game losses.
Latias:OU. While it does have access to a fairly large special attack movepool, it is countered fairly easily by Scizor which is used on many teams. Weavile can also OHKO it and outruns it unless it is a Choice Scarf variation of Latias. Tyranitar can also keep it in check due to its natural bulkyness plus having a high physical attack stat to ko Latias. Unlike Garchomp, Latias can't function that well as a physical sweeper. It also has a lower sweeping stat despite it being faster than Garchomp.
Manaphy:OU. I am voting OU for Manaphy because unless there is rainfall, it can easily be defeated. Without the continuous rainfall that Kyogre can provide, it is unable to use the cheap Rest then attack next turn. Teams would have to be dedicated to rain to make it work effectively and would need to have one or two Pokemon hold Damp Rock. Jolteon, Zapdos, and Raikou outrun it and have a powerful special attack stat. Starmie resists both Water and Ice attacks commonly found on Manaphy. It is also capable of Electric attacks to inflict a large dent in Manaphy's HP. While Tail Glow is a great move in that it raises the Special Attack two levels, without being able to do the Rest trick, it loses some of its luster. If it was voted OU by the community as a whole I would expect to see more Calm Mind for the reason of making it bulkier and possibly Ganlon Berry with Rest so its regular defense increases.
[Colin edit: I updated the totals to include the three votes by super moderators and admins (Aeolus, TAY, and Hipmonlee), which were initially ignored due to a bug in my script. I apologise for this mistake; however, it did not affect the outcomes.]
A reminder of the new Stage 3-2 proposal:
Two simple majorities in a row in the same stage to consider a pokemon uber
This condition means that a pokemon has to be voted uber by a simple majority twice in a row within the same stage of suspect testing to be considered uber. For example, under this condition, Garchomp is allowed into the next round of stage 3, but if he is voted uber by a simple majority again, he is declared uber.
If we choose to proceed in this direction, then we can also set an arbitrary ratio > 50%+1 that, if achieved for the "uber" side, allows a suspect to be declared uber without a second round of voting.
As a corollary of supporting this condition, a suspect is not considered to be uber until it has voted uber by simple majority twice in a row in the same stage of suspect testing or voted uber by a supermajority > 50%+1 to be determined later (e.g. 2/3+1).
The only Suspect that had been voted Uber in Stage 3-1 was again voted Uber, and neither of the other two Suspects reached the agreed-upon critical ratio (2/3 + 1). Therefore, in concordance with the proposal for Stage 3-2, Stage 3 is now over. Latias remains OU and on the Standard Ladder, Manaphy is now considered OU and will be included on the Standard Ladder as soon as possible, and Garchomp is now considered Uber and will remain banned from the Standard Ladder.
I'll close with a brief reminder—we aren't yet done with the Suspect Test. We strove first to sort out the individual pokémon before addressing the long-enduring competitive clauses that had been given even less thought than the tiering of individual pokémon. These clauses and how we will test them will now be addressed in Stage 4.
After speaking with Aeolus and other Tiering Contributors over the past few days, we are considering holding a Stage 3-3 where Latias and Manaphy will be tested together. Logically, this is of course the correct thing to have done yesterday.
I trust you won't perceive it as defensiveness when I cite our decision to add Latias to the Standard Ladder earlier this year after its OU Stage 2 tag as the only reason I felt it a virtual non-issue to similarly move Manaphy to the Standard Ladder. I and we have changed many, many things during this test on the fly, and this probably won't be the last reconsideration that's made during the Suspect Test Process.