Probably the most viable choices we have right now of the ones given are:
-TGMD's BU Conkeldurr (bulk up, payback, drain punch, mach punch)
-alexwolf's Bulky Jirachi (u-turn, iron head, wish, thunder wave)
-Heist's Eclectic Jirachi (iron head, thunder, hp ground, icy wind)
-Melee Mewtwo's CB Swampert (stone edge, waterfall, earthquake, hammer arm)
-Halcyon Of Light's YacheChomp (swords dance, outrage, earthquake, fire fang)
-My CB Chomp (outrage, earthquake, fire fang, dragon claw)
The likely counterpicks to these, respectively, are:
-Gliscor, Landorus-T, Latias, Latios, Reuniclus
-Gastrodon, Ferrothorn
-Gastrodon, Ferrothorn
-Tangrowth
-Weavile
-Weavile
Really, I think we should eliminate Yache Chomp because the Yache Berry isn't a very useful item if they just counterpick with Ice Punch Weavile. Life Orb or even Leftovers are better choices for an SD Chomp's item, and if Halcyon of Light changed the item it might well be better than CB.
Right now I don't really love the Swampert choice, not just because it makes Tangrowth a problem, but because, as a slow Pokemon, it can't take many hits and will be killed off rather quickly. The fact that it does have a hard counter (thanks to Regenerator even Ice Punch isn't a problem) in Tangrowth only exacerbates this. Swampert's Speed and lack of recovery. It's a great Zapdos switch-in, but it can only do this so much.
Though it seems similar to Swampert, Conkeldurr is a choice I can get behind. With Leftovers and Drain Punch for recovery and no need to lock itself into a move, and the ability to set up, it has a lot of the things Swampert lacks. Landorus-T and Gliscor aren't troubling counterpicks as we have Slowbro. The Latis are a bigger problem, though they won't take a Payback well. Reuniclus is probably the best pick, as a CM Reuniclus can shrug off Paybacks easily enough, while TR variants can set up Trick Room and start crushing things. However, both of these still have flaws.
Both Jirachi sets are pretty neat, but the fact that Gastrodon is a pain in the ass to our other two members is unavoidable. On the other hand, Gastrodon can easily be dealt with using Grass-types. In particular, Celebi can do whatever it wants with its moveset, which means Gastrodon isn't the worst thing that can happen for Team 1.
Garchomp puts insane offensive pressure on the opponent, but unfortunately allows the opponent to do the same to us with a powerful Weavile counterpick. Once it's in, it can probably get a kill, but getting it in will be somewhat difficult.
Right now it seems to me that we should pick Jirachi. alexwolf's Jirachi is a good Zapdos switch-in, passes wishes, keeps the momentum with U-turn, and paraflinches very well. While Conkeldurr has a lot of great qualities as I mentioned, it makes our team rather weak to Zapdos, which could be a problem.
I do have a suggestion for Jirachi's moveset though, and that's Body Slam. Since Slowbro already has Thunder Wave to spread paralysis, Jirachi can dissuade Ground-type switch-ins like Gastrodon (A PROBLEM), with a 60% paralysis chance. Though the 60% chance isn't great normally, it's much more useful to hit Ground types since we already have 100% para move, and a few timely flinches can spell the end for even Gastrodon, as Heist mentioned. Gliscor also won't want to switch in to this Jirachi without activating its Toxic Orb as paralysis will totally cripple it.
Thoughts about this? Why isn't Jirachi a good choice? And is there a good reason to keep Thunder Wave on your Jirachi, alexwolf?