For the first paragraph, I'd suggest reading EonX's post. Furthermore, Adamant LO Hitmonlee has a less then 10% chance of 2HKOing Doublade with Knock Off and Kabutops less then 1% if they have no hazard support. In return, Hitmonlee has a fair chance of being OHKOd by Iron head assuming it's at 100% (ha) and Kabutops takes 80% minimum if it's a Weak Armor variant from a Iron Head+Shadow Sneak combo (70% if it isn't). So, assuming they predict perfectly 100% of the time, they still can't beat it bar lucky rolls. The fact that Shuckle only gets 2HKOd by some of the hardest hitting mons in the tier (or those with STAB SE moves) means that it will always will get SW up (and more often then not, SR as well) and raise hell against Offense (who uses the spinners I mentioned, who can't KO Doublade reliably). Defoggers are meh on Offense unless they forgo hazards of their own. The last options mentioned can be applied to nearly everything laying 2+ hazards.Looks like I'll be (to my surprise) going against the grain here when I say that I don't think Shuckle is broken.
People seem to think it's basically impossible to prevent Shuckle getting both Web and Rocks down, which simply isn't true for anything but Stall teams, who generally don't care about Web being up anyway. There's essentially 2 ways to stop both layers going down for Offense, Xatu or simply 2HKO'ing it, neither of which are difficult. Hitmonlee and Kabutops are both Spinners that can 2HKO Shuckle, and can punish Spinblockers coming in with powerful Knock Offs, then theres Rhyperior, Sharpedo, Magneton, Amoonguss (Spore), Clawitzer, Cincinno, Durant, Archeops are all completely viable mons on offense which can prevent 2 layers, then depending on the spread Doublade, Escavalier too. There's also things like Knock Off + Taunt Mega Banette, or Switcheroo Delphox/Trick Rotom-C/Trick Zoroark.
As for Shuckle being bulky enough to come in later in the game, this for the most part isn't true since you should of landed a big hit on it first turn as it set down Web, as well as the fact that its so slow that anything it comes in on its going to have to take 2 hits from, and finally it's weak to Rocks. Now obviously people don't have to lead with Shuckle, but since they're team is so reliant on Web being up to outpace things they can rarely afford not to.
Now if you're running Offense and Shuckle has managed to get Web down and you can't find opportunities to remove it, there's still plenty of pokemon which can still trhive. Scarf Rotom-C and Scarf Moltres especially but also non Scarf variants are basically guaranted to outspeed everything, even Scarf grounded pokemon like Delphox can outpace standard web mons with Web up. Outside of Scarfers you still have Yanmega, Fletchinder, Mismagius, Vivillon and Sigilyph which can outpace and punish mons so reliant on Web. There's also tons of priority available with Zoro/Lee/Gurdurr/MegaSnow/Kabu/Doublade/Mega Banette/Zangoose.
All this combined with Shuckles 0 offensive presence leads me to believeing Shuckle isn't broken. Web itself or Exploud/Yanmega have far more justification for a ban than Shuckle, though I don't think any of them are ban worthy
Oh and I do agree with Shuckle teams being a bit stale, but that is the fault of the playerbase choosing to use them, not the fault of Shuckle.
Edit: If Shuckle is banned then Leavanny should be the replacement, since if knocked down to Swarm it's X Scissor can be quite powerful, it's the fastest Sticky Web user available, and finally it has access to Magic Coat to bounce back Taunt and SR.
Second paragraph's point is pretty valid, can't really say anything against that, although considering that offensive spinners can't beat Doublade reliably anyway and Defoggers get screwed over by Braviary, often it doesn't have to set SW up more then once.
There's only Levitate mons and exceptions like Sigilyph that don't mind Sticky Web AND Stealth Rock. The rest gets screwed over real hard by the latter. Most SW team members don't mind priority if not SE as they do have some semblance of bulk and most of these have issues anyway. Zoro and Lee can get outpaced by an opposing Lee and Mach Punch'd themselves, on top of having issues switching in (but it's HO these usually are on, so meh). Hell, over half of these have issues against Lee under SW and others, while also needing a turn to maximize their power (the Mega's, Zangoose). Doublade is also terrified of Exploud coming in for free, among others.
And, no. Leavanny won't replace Shuckle, for two reasons. 1. It lacks the bulk to run Mental Herb so needs to rely on Magic Coat (prediction, basically) to bypass Taunt and other nasty things. Also gets fucked up by Cincinno. 2. Has really poor coverage and can't stop things from setting up on it due lack of Taunt/Encore (unlike, say, Accelgor :3). Not sure how it's gonna be a poor man's Shuckle with those flaws. Any other Sticky Web setters are even more flawed so I won't go into them.