[Porii Sames]

Well let's see here.

Mewtwo has a somewhat low chance of generally pulling back a comeback, but it's possible. The only thing is it's normally LO and it's also physically weak, meaning that it might be able to OHKO most the metagame, but any hard hitting, Scarfed physical attacker (Hell, LO EK Arc for that matter) coupled with LO damage means Mewtwo can't make the legendary comeback (although it is a GREAT LGS.)

If anything, the best LGS Dialga set I can think of is OTR Dialga, but that can't really sweep 6 mons, now could it? Cro-Dialga with Bulk Up is probably a close second, and I'd say it could have a pretty good shot and is one of the more likely comeback pokes that I'm seeing on here.

With some very, very good luck and good team-weakening on the opponent's side, Scarf Zekrom can actually pull off a comeback if its checks and counters are weakened, and it doesn't get confusion hax in the form of Outrage. However, that's all pretty unlikely, and normally means that Zekrom doesn't have much hope. Sub-Hone Claws could actually work pretty well in this case, there's no shortage of things it can set up on, after all.

Ho-Oh....just has a few too many checks. If you break it sub at all, ScarfOgre is free to come in and make life hell for it (iirc Timid Scarf Water Spout always OHKOs even after Ogre has taken Rocks) and you still have a variety of things that can check it, such as Palkia or in general anything that can take a hit and has either a decently strong Dragon move that can break its sub or has a Choice Scarf and is capable of threatening it so it cannot play the Subroost game. In the sun, it has a much better chance of sweeping, but it's still shaky at best.

I honestly have never seen a Manaphy sweep a team. I'm sure it could, but...well maybe it can't. Scarf Ogre pressures it, Mewtwo pressures it, Arc pressures it, everything that really hits hard pressures it and makes it so it can't just Hydrarest all day. A CM set might also be a good alternative though, and could provide the comeback, but you still have a host of checks and counters to that too. Ferro basically fucks over any Mana set anyways though.

If they don't have Ogre or Groudon, Excadrill is actually pretty good as a LGS. If you pull off an SD, there's not really a whole lot that can stand in your way; barring the usual things like Landorus-T and Gliscor. I'd definitely put Excadrill reasonably high on the list. But of course without sand, it's GG Exca.

Groudon, as mentioned earlier, is another one of those mons that has a very good chance of sweeping. Double Dance can take out a number of threats, the only problem being that it really wishes it could run LO; EQ at +0 with a Lum Berry just doesn't always hit hard enough, especially on things like Ogre where you NEED to OHKO or things like Arceus where if you don't OHKO you take an insane amount of damage. Groudon's still pretty high up there.

Giratina-O, again as mentioned before, is bulky enough to take a hit and dish one out. It's normally seen, at least to me, as something that can kill something and maybe dent another. A great mon, awful comeback poke.