Hello! You may have noticed if you've interacted with this tier for about five seconds that hyper offense is really good in this tier. And you may notices it uses a lot of the same few Pokemon! This is gonna be a pretty surface level overview of the roles each one aims to fill and why you might want or not want to pick them for your team, including some of the more niche playstyles such as Weather, Terrain, and Sticky Web.
This is where you determine exactly which style you're picking, obviously. The most common and best one in the tier is "standard" hyper offense, where you load up 1-2 setters and go, so let's start there.

Kleavor is probably the most common setter, or at least was before the metagame adapted back to it. Its main draw is Stone Axe, which ignores Taunt and the rare Magic Bounce Espeon while giving your setter more offensive presence to threaten potential defoggers such as Talonflame with. However, Stone Axe can miss, which isn't common but isn't ideal, it's the slowest hazard setter and therefore can be played around that way, most notably with Rock Blast Terrakion, and most importantly despite its power there are certain things it can't really touch at all, including common setters such as Hippowdon and the new Galarian Weezing, making it weaker into defensive teams than certain other setters despite its offensive prowess.

Terrakion is my pick for the best current Stealth Rock setter on standard HO, with its SD/Rocks/Rock Blast/Close Combat set. While it misses out on Stone Axe (despite having literal stone axes on its head) and is therefore more susceptible to standard hazard counterplay, it's much more immediately threatening than Kleavor and significantly faster. Loaded Dice Rock Blast allows you to beat prominent sash leads such as Froslass, Kleavor, and the Sticky Web brothers in the other HO matchups. What puts Terrakion over the edge compared to the others is it's also a breaker that naturally forces switches for SD/Rocks, meaning it can come set or even punch holes in the midgame and gives it much better role compression. Terrakion is also the best HO Stealth Rocker to pair with leads that don't set up stealth rocks due to this.

Krookodile has access to Taunt, Rocks, and a very good dual stab combo, but is the slowest of the HO leads that wants to click Taunt and generally outclassed by Terrakion outside of its access to Knock Off.

Lycanroc is a pretty uncommon lead but its access to Taunt, Rocks, and Accelerock while also hitting very hard with tough claws and even having some set versatility with its good coverage, Taunt, and Endeavor. Endeavor + Accelerock is cute. Don't use midday lycanroc seriously but it is faster than Froslass and can taunt it I guess.

Azelf is the fastest lead in the tier, and therefore has the fastest Taunt into other leads or defensive teams, and is decently strong with a fairly wide utility movepool, although you'll mostly be setting rocks, clicking a move if you can, and blowing yourself up after you're put to 1 HP. Azelf can also forgo the traditional suicide lead set for a more offensive rocks set with Life Orb or even forgo rocks entirely and be a setup sweeper, but unlike Terrakion it usually has to pick between rocks and NP. It's also a reasonably effective screener, although screens itself is a pretty ineffective playstyle.

Mew is, functionally, a much slower Azelf that sets both Rocks and Spikes, and is the only HO lead worth talking about that does so. It's also reasonably bulky, enough to not have to carry a Focus Sash, and thus can run other items like Red Card or Mental Herb to help check other options. Outside of setting hazards and dying as fast as possible, Mew also has insane versatility as a setup sweeper due to, well, being Mew, and it can even set screens, although I would consider Klefki or Espeon to be the best screens setter.

Froslass probably has the highest ceiling of any of the leads despite its inability to set rocks. While others such as Terrakion, Kleavor, and Azelf are able to exert offensive presence, a well-played Froslass usually garauntees a kill thanks to Destiny Bond. in HO vs HO matchups, it's faster than every lead bar Azelf and is thus able to taunt them (or dbond 50/50 with Terrakion), which is also hugely useful. Outside of DBond shenanigans it exerts zero offensive pressure and can't set Stealth Rock, so pairing it with Terrakion or Krookodile is very common. You also can't be spun on and its access to a fast taunt means

Galvantula really should be ranked, as it's a very fast webs setter with hard hitting STAB moves and a good chance of paralysis with thunder. Most notably compared to Araquanid, it speed ties terrakion and outspeeds at least a few taunt leads, letting it potentially get webs off in matchups Araquanid would fail to. It's also the webs setter on the current sample!

Araquanid is the other best webs setter, trading Galvantula's speed for more bulk and power and access to Endeavor and Mirror Coat for a nasty surprise for the opponent. Like Mew, it's also bulky enough to get away without a focus sash if you so desire. I personally prefer Galvantula's higher speed stat given how many taunt leads there are.

Klefki can set spikes, but is mostly used to set Dual Screens since it's garaunteed to get at least one off without dying and has other cute utility moves like the aforementioned Spikes, Thunder Wave, and Steel Beam to die faster and garauntee a free entry. Screens is pretty unviable right now but it's worth mentioning here.

otherwise somewhat dead slots required for their team styles to actually function. I don't plan on talking about these that much compared to the standard set up thing-sac a mon-go nuts style since that's the most viable and this post is already gonna run long as it is. Sun is also set to get a massive bonus with Torkoal in a month or two, that's cool.
Keep in mind, this is a non-exhaustive list. There's too many of these guys to cover in one post. Don't be afraid to get creative! For the most part, on "standard" HO, speed creep means that most of these are either >100 speed and boosting to +1 speed, or under it but boosting to +2. Generally, you have room for 2-3 of these alongside your setter and 2 offensive utility mons.

I'm gonna try not to turn this into ban Blastoise post #65535 but there's a very good reason Blastoise anchors more or less every serious HO team that isn't relying on an alternative gimmick (Webs/Screens/Weather/Terrain) to win. Shell Smash Blastoise is the single most threatening Pokemon in the tier to any playstyle due to its absurd power, bulk before setting up, and mind-meltingly high number of possible tera and 4th moves making it nearly impossible to scout until it's too late. Blastoise is your main sweeper and your entire team is usually built around taking advantage of which of the usual checks your Blastoise set beats, and tailoring the rest of your team to either beating the other potential checks for it and/or taking advantage of the holes it leaves behind as a midgame sweeper.

broken car go brrrrrrrr. A lot. While it doesn't have quite the set diversity of Blastoise, it does at least have some coverage mixups (usually iron head/tera blast). But for the most part it just has a near-unresisted coverage combo in poison/ground, a really good defensive typing with its air balloon up, and therefore really easy setup opportunities. It only needs a single shift gear to get going, and has some of that juicy 30% chance to fuck your opponent over with gunk shot poisons or iron head flinches we all love.

the third broken! Unlike the other two above it and a few below it, it has practically no mixup on its coverage and usually needs tera, but the upside is the single scariest non-blastoise sweeper in the tier. A well-played Yanmega is also very resistant to priority and revenge killing due to stacking speed boosts, protect to dodge first impression, and high enough bulk to take neutral priority moves without much trouble at least once, making it incredibly difficult to stop for other offensive teams. Air Slash is also a broken move that lets you beat any of your checks if you're brave enough. Blastoise, Yanmega, and Revavroom are staples of HO and one, two, or even all three are usually on every hazard stacking HO team.

is kind of an exception to the speed rule, which is generally its biggest flaw as it's more liable to revenge killing than some of the others here, but it makes up for it with a very wide coverage movepool and even some cute utility options such as Prankster Taunt and Thunder Wave. Outside of TBolt and Grass Knot, it also can use Sludge Bomb, Focus Blast, Psychic, or even Tera Blast if you want, making it pretty hard to scout for teams that aren't able to outspeed its base 111 speed naturally.

the best worst mon of all time. While some of these mons can hugely benefit from RNG with secondary effects, Hilligant's is a double-edged sword that can make it insanely strong but also it can just miss and screw you over hugely (can you tell I've been using this mon recently?). Teras Fire, Rock, and Ice are all viable sets for it, giving it a good bit of unpredictability outside of the rng inherent in a hustle mon. Another cute thing is Victory Dance's defense boost actually helps it live priority should you not be weak to it, which can make it deceptively difficult to stop. Sadly, it's a victim of Okidogi's success currently since the sheer amount of defensive Tera Poison mons can ruin its fun.

the star of psychic terrain, but also very good on standard HO with either Calm Mind Weak Armor, or Endure Weakness Policy more commonly, creating a different scout situation than most of these since it's gonna be hitting you with the same attacks regardless and trying to revenge kill it can end very badly without priority. If it's not on a psychic terrain team, WP Endure is also extremely vulnerable to priority outside of being able to Endure through First Impression from slither wing, which can make it occasionally fragile. Grass/Fire/Psychic coverage is incredible for this tier, too.

Grouping these together since they use the same boosting move and two abilities. Moxie snowball sweepers are fairly uncommon compared to the above ones since they're a little more feast or famine but they're still good! Gyarados in particular has been trending upwards in general recently, not just HO. Both of them have huge coverage movepools, with Gyarados additionally having Taunt to screw up certain defensive mons if it wants to, and both of them can also pivot to Intimidate for easier set up opportunities. The one you pick depends on your team, with Gyarados in particular struggling with bulky waters without tera and Mence having to go very deep into its coverage pool if it wants to beat Geezing.

Also kind of similar. Daunt hits harder but Gatr is bulkier and sets up easier. Both of them can pick between DD and SD, although Daunt in practice is too slow for DD compared to Gatr. Gatr in particular is kind of a midground between Gyarados and Crawdaunt, which can make it struggle to stand out, but they're probably all about as decent as each other.

necessary for their playstyles to function but bad everywhere else, so I'm not gonna talk about them much here. Maybe I'll make a weather menu down the line.
some other options include the aforementioned

and

, as while as

and more for more niche choices.
This is kind of an "Everything else" spot for stuff that isn't really a sweeper or a hazard setter but still finds its way onto these kinds of teams pretty often. Usually these constitute hazard removal, hazard removal denial, and more dedicated revenge killers, as while as offensive checks to important stuff. These generally constitute 1-2 slots, with Mimikyu in particular being up there with Blastoise as most central to the entire playstyle.

only does everything. While it's too weak to actually sweep anything besides opposing HO, the combination of its native ghost typing to block hazards, phenomenal defensive typing, and garaunteed red card trigger (except vs multihits or necrozma...) make it an incredible utility mon with huge role compression and a one-time check to nearly every dangerous setup sweeper in the tier. Mimikyu probably has the highest usage of anything here as an offensive check to literally anything letting you save a ton of space in the builder, even if its actual offensive prowess is pretty middling.

While Mimikyu is your usual rapid spin blocker, these two are your usual defog deterrents, especially Bisharp due to its surprisingly high bulk with Eviolite and strong priority to make up for the speed difference. Unlike Mimikyu, Bisharp actually can sweep a team if you're good enough at sucker mindgames, while gapdos much more falls into the Revenge Killer category that I'll talk about later.

unless you're insane enough to run Smash Spin Blastoise (protip: don't), this is the only real method of actually removing hazards HO runs since none of our spinners are super helpful to the playstyle and defog is unviable here since you don't wanna remove your own hazards. Both of them share Technician, Tidy Up and Encore, but Maushold is stronger due to population bomb being broken and is therefore usually run more. Cinccino differentiates itself with access to Knock Off, U-Turn, better coverage, and not immediately dying to rocky helmet, but it has severe 4MSS and can't run all of them at once. It is also notably faster, getting over thundy-I is really nice. One of them is also pretty integral to psychic terrain and/or sun, which appreciate getting hazards off much more than HO (although they can also run other spinners a bit better)

HO focuses more on denying your opponent the ability to set up hazards early game than outright removing them, and Espeon is decent at that. It's not really bulky enough to abuse it much but just having it in the back makes clicking them a huge risk. It's also a great fit on psychic terrain thanks to access to Expanding Force and Armarouge's hazard weakness for the Endure set mandating removal more than the average HO team, and you can even go full gen 5 and put it on sun if you want to. Lastly, it's also probably the best non-klefki screens setter in the tier, since it blanks hazards while doing it, even if it's kind of squishy.

really good on rain for the role compression and mutual synergy, and really bad most everywhere else. This is generally how rain both lays hazards and gets them off.

While Mimikyu can usually cover it, sometimes you want a more dedicated revenge killer, and that's where this category comes in. I singled out these three in particular since they're the most common, but most anything with strong priority or a fast enough scarfer like Gapdos or even Espeon can work too. Gardevoir is kinda slow for fast revenge killer standards, but is usually fast enough to get the job done, STAB moonblast from something with an actual spa stat forces very linear play, it comes with utility like Trick and Healing Wish, and trace makes it very useful in the weather matchups. First Impression just forgoes any guesswork about speed and always goes first, and slither has a bunch of sets it can run, but it's completely useless vs yanmega and slither in general is quite slow outside of Fimp, so your mileage may vary. Barraskewda is just a good fast pivot all around while being the centrepiece of rain, it helps rainproof your team and of these four specifically it's the least screwed over by Yanmega clicking protect on it since Tera STAB Aqua Jet really hurts it. Jirachi can theoretically also set rocks and be a setup sweeper, but in practice I think scarf fits the best on HO. It's very fast, has a great defensive profile for an offensive mon, can trick and pivot, and comes with that delicious 60% flinch chance if you want to win faster.

Lastly, I don't have anywhere to put this since it's a huge outlier, but Volcanion is a solid pick for being a strong breaker, offensively checking Blastoise (as much as one can, Blastoise can kill it with Tera Electric Tera Blast or EQ, but if it's not running that you're good) and taunt shutting down boosting sweepers like Slowbro and Reuniclus that can otherwise give you a headache, so it's a decent way to plug holes on HO despite not really fitting into any general HO "category"
God I said this would be a simple breakdown and nonexhaustive and this still turned into a novel. Hopefully this is a general guidline to help you get started, but don't be afraid to experiment! Maybe you can be the one who breaks the tier with like, Agility PZ or something. Go nuts!