I've been ninja'd twice, and perhaps this is a question that can be answered without doing a long list, but in case he wants to know why all of these Pokemon are used without looking it up, I'll right short paragraphs for most of them. Let's do this thing. First we'll start with hazard setters.
Deoxys-D is an extremely successful Pokemon because of its ability to act as a hazard lead with access to both Stealth Rock and Spikes. Its bulk and ability to either run a Mental Herb or Red Card guarantee it to set up at least Stealth Rock and two layers of Spikes. He functions best on heavily offensive teams, as although he has little offensive presence himself he is often sacrificed after he has laid down hazards, providing momentum. He can also lure in Bisharp (a common anti-lead against Deoxys-D) and OHKO it with Superpower.
Deoxys-S is not good when only being used as a hazard lead due to its frailty, which means that it won't be able to set up enough hazards for most teams. However, he is often used as a lead on rain teams (to set up rain) or dual screen hyper offense teams (to set up Reflect and Light Screen). He is often carrying Stealth Rock as well on those teams, allowing him to provide both hazard and rain/screen support for those teams. A more offensive version with 3 attacks and Stealth Rock is good as well.
Garchomp is a Pokemon that is used on heavily offensive teams that either don't rely as much on hazards to use Deoxys-D, don't like that Deoxys-D almost always needs to be sacrificed to provide momentum, or want a hazard setter with more offensive presence. His good offensive typing and access to strong attacks as well as Stealth Rock make him a good choice for teams that only need Stealth Rock.
Similarly to Garchomp, Mamoswine is an alternative choice to Deoxys-D for some teams. In addition to setting hazards, Mamoswine also has the ability to revenge kill many common Flying-, Dragon-, and Ground-types.
Terrakion: See Mamoswine and Garchomp
A choice for more defensive teams is Ferrothorn. While Ferrothorn has the ability to run both Stealth Rock and Spikes, it usually doesn't because of its inability to rack up enough damage with them, as it doesn't have a phazing move. However, Ferrothorn also has access to Leech Seed and checks or counters many Water-, Rock-, and Fairy-type Pokemon.
Another choice for defensive teams is Chansey, who sets up Stealth Rock. Chansey can easily switch into most special attacks and force the attacker out, meaning a free turn to set up rocks.
Skarmory is yet another choice for defensive teams. In addition to setting up Stealth Rock, Spikes, or both (although usually not both because using both often leads it to having four move-slot syndrome) it can also remove hazards with Defog or shuffle the opponent's team to rack up hazard damage. It also counters or checks many physical attackers that don't commonly carry attacks it's weak to, most notably it counters Mega Pinsir.
Heatran is another one of the best choices for defensive teams for its ability to set up rocks and phaze. Its phazing also allows it to spread toxic on the enemies team. It also has the ability to check about every Fire-type not running Earthquake in addition to Pokemon that rely mainly on Flying-type moves.
Okay, last choice for defensive teams. Hippowdon, like Skarmory and Heatran, has access to both hazards and a phazing move. Also like Skarmory but unlike Heatran it has a recovery move in Slack Off. It also has great mixed defenses when invested in, allowing it to absorb many attacks for its teammates and recover. Lastly, it is immune to Electric-type moves and can beat most Fire- and Steel-type attackers as well.
Shuckle is a little bit of a different hazard setter. It isn't seen often but provides good support for the teams that use it. Shuckle's sheer bulk means that it can almost always set up Sticky Web and Stealth Rock for teams with slower but powerful Pokemon. It can also prevent itself from becoming set up bait with Encore.
Landorus-T is a Pokemon that acts as a pivot for bulky offensive and balanced teams, and as a slow U-turner for Volt-Turn teams. Its ability to pivot into most non-supereffective physical attacks due to its ability, Intimidate, and to hit back hard make it a nice choice. Because most Pokemon that Landorus-T switches into will switch out in fear, it has many opportunities to set rocks.
Non-mega Tyranitar is another great Stealth Rock user for bulky offense and balanced teams alike. It has priceless resistances to Fire-, Flying-, and Dark-type moves, meaning that it can switch into many physical attackers, similarly to Landorus-T. As they switch out it can use Stealth Rock. It also can Pursuit trap Pokemon and set sand for sand teams.
Now onto hazard removers. There are many more viable removers than setters, so I'll only cover a few of the best ones. Other choices include Mew, Starmie, Mega Blastoise, and Kabutops. Mega Absol can also bounce back hazards as they're being set.
While the Deoxys formes can't actually remove hazards, their access to the moves Taunt and Magic Coat means that they have the ability to prevent other Pokemon from setting up hazards early-game.
Without a doubt the best hazard remover is Excadrill. Its ability to defeat all relevant spinblockers combined with its versatility and access to Rapid Spin means that it is very successful. Its Mold Breaker ability allows it to defeat levitating spinblockers like Gengar, in addition to Aegislash. However, Aegislash can run Air Balloon, but Excadrill can also run Shadow Claw. It can also act as a revenge killer with a Choice Scarf or just as an attacker with Life Orb. It's best on offensive teams that need hazard support but don't want to use Defoggers (as Defog removes their own hazards as well).
Another great hazard remover is Latios. With great offensive stats, it is a wonderful Defogger for offensive teams. It can also feign an all-out attacking set as well as provide its team mometum with Memento, creating an opportunity for a sweeper to set up.
Latias is similar to Latios, but slightly different because of its access to Healing Wish, which means that it can fully heal a weakened Pokemon on an offensive team. Unlike Latios, Latias will never be running an all-out attacking set and will always have Defog.
Mandibuzz is yet another Pokemon with Defog, although it's best situated on balanced or defensive teams. It can also counter/check Aegislash, one of the most dangerous Pokemon. In addition to Defog it can also heal itself with Roost (although most Defoggers can do this) and use Foul Play, Knock Off, and Toxic.
Skarmory is a defensive Pokemon with Defog, as previously mentioned. It is the only Pokemon that commonly both sets and removes hazards, as most Pokemon with access to both hazards and Rapid Spin/Defog usually have something better to do (such as Excadrill) or are not OU viable (such as Forretress).
Zapdos is more comparable to Mandibuzz as it fits on both on both defensive and balanced teams. However, unlike Mandibuzz (and most other Defoggers), Zapdos beats Bisharp and Thundurus, the two main Defog discouragers, much more easily and with more consistency.
Mega Scizor is another good Defogger, that fits on all sorts of teams, can feign an all-out attacking set or Swords Dance set, and has the ability to defeat Bisharp at the very least, although it will often have four move-slot syndrome. Because it's a mega, you unfortunately can't put it on ANY team.
As for your other question, in addition to what has already been stated, special attackers also tend to have less bulk than physical attackers, and there are less Pokemon that can wall physical attackers due to the fact that many of them carry boosting moves or can also go mixed. However there are still many special attackers which are just as dangerous as physical ones, including Greninja, Mega Charizard Y, Landorus, Keldeo, Clefable, Gengar, Aegislash (who can also be mixed) and Latios.