Alright
Froggyboy let's get this done. Lilligant has several things going for it that few other setup sweepers have. First off, it already has great offensive stats off the bat, with potent Special Attack and respectable Speed. Then it has one of the best boosting moves in the game in Quiver Dance, which not only bolsters its offensive potential but also softens incoming special blows. But most notably, Lilligant is a setup sweeper with
great self-sustain in the form of STAB Giga Drain, which is crazy good for a 'bulky' setup sweeper and goes a long way in either preserving itself long enough to go for the sweep or to evade revenge kills. It also makes Lilligant one of the few setup sweepers to set up in the face of Scald users since it can usually keep itself healthy enough to stave off the burn. You'd be surprised at how well boosted LO Giga Drain lets Lilligant stand up to a good majority of the tier because of this.
I see that Quiver Dance with Sleep Powder is a deadly combo, and thats why I am not nomming it any lower, but Sleep Powder can be unreliable at times, and even at +1, Lilligant's bulk isn't anything to really get scared at. And while a scarf set with Healing Wish is pretty neat, it still has no coverage outside of Hidden Power, leaving it very predictable
Alright, I probably shouldn't of said wall, but it is easy to check. I mean, every decently made team has something for Lilligant, like Xatu, Typhlosion, Mega Camerupt, Mawile, Garbodor, Scyther, Jynx, Klinklang, Magmortar. Every team should have at least one of those Pokemon, and they make Lilligant's job more difficult.
I understand Lilligant is a great late-game sweeper, but I feel its typing, low BP moves, and predictability make it move down to A rank.
The fact that it is a setup sweeper with access to a decent sleeping move means it can usually just immobilize most Pokemon that get in its way, rendering them easy prey for teammates or simply prevent them from disrupting Lilligant's immediate / later sweep. You say the +1 special bulk isn't really anything to get scared at, until you have a Lilligant set up right in front of your Ludicolo or Samurott or whatever. And while Lilligant's coverage is obviously its most notable issue, it really isn't a big deal since not only does Lilligant have its hands full in terms of moveslots as it is, but boosted Giga Drain carries Lilligant through many unresisted opponents as it is, so only having Hidden Power as its coverage move isn't really detrimental to Lilligant's success at all; it just wishes its coverage move had more power, and Hidden Power can shave off a good majority of those checks as is, meaning you only have to cover for the remaining stragglers.
I'm sure any sweeper can be threatening after its wall are gone, but it isn't as easy as just saying that.
Assuming you have put a Pokemon to sleep to find an chance to set-up, and the opponent switches out into their Typhlosion, you can't put that to sleep too because of Sleep Clause, so you are either forced out, or OHKOed by the incoming Fire Blast or Eruption. And I will agree that Giga Drain is nice for keeping it healthy, and is surprisingly strong at +1.
It's not just Fire types that can threaten Lilligant, most scarfers have a way of forcing it out. Mespirit can 2HKO with Zen Headbutt or U-Turn out, Jynx has Ice Beam and Lovely Kiss(granted its a speed tie iirc), Haunter has Sludge Wave, Tauros can OHKO with Double Edge after 1 round of LO and rocks. And while Hidden Power is nice for taking out Grass types, it leaves Lilligant very predictable.
It seems you are under the assumption that Liiligant
needs to put something to sleep in order to set up, when that is not the case. Realistically you have Lilligant set up on a Water-type / Ground-type which the opponent will have, and gain back most, if not all of the health lost with one fell swoop, while making use of the special bulk increase to further lessen the damage. As for the Scarf checks, none of them want to switch into a Sleep Powder, so mindgames ensue as you try to predict whether Lilligant would Sleep Powder or Quiver Dance: switch your Scarfer into the Sleep Powder and that spells trouble, while staying in expecting to absorb the Sleep Powder only to be met with a Quiver Dance can be disastrous if it gets the chance to Quiver a second time. You see what I'm getting at here? Win the prediction and you can force Lilligant out, but losing the prediction war can very well cost you the game.
Also lol Scarf Mesprit is not even a check to Lilligant, Jynx does not speedtie Lilligant but needs a Scarf to outspeed (and even then Scarf Jynx fails to OHKO +1 Lilli with Ice Beam), and Hidden Power is not
solely for Grass-types if they aren't a huge issue (can be opted for HP Rock which smacks a lot of the checks u mentioned). And really, Lilligant has more problems with Poison-types than Grass-types if anything else.
Plus another reason I made this nom is because I don't really see being on Samurott's or Sneasel's level of viability. I don't doubt its a viable Pokemon and one to look out for when teambuilding, I just don't see it as A+, which is the border between A and S.
Between its already great offensive stats, terrific boosting move, the fast sleep, and insane sustain for a setup sweeper, Lilligant is definitely up there as one of the most potent setup sweepers in the tier, and is the reason people have considered it for S (and I don't blame them). The largest issues that come to mind are its physical frailty and its coverage, but its longevity helps against the former and it's not even the
lack of coverage that bothers Lilligant, rather the
strength of its available coverage.