In Pokémon Black, Sawk can be found in Routes 10, 15, 18 and the outside of Pinwheel Forest in both the normal and the dark tall grass. They are relatively rare, having encounter rates from 10-15%. In Pokémon White, they appear in the same places, but only in the rustling tall grass. Here, their encounter rates are all 5%.
Sawk is easily the strongest Pokémon you can get before the second Gym. Carrying a BST of 465, this Fighting-type destroys everything that dares oppose it... and that includes your own team. In the early game, Sawk is god-tier, but in the late game he's not bad either. Boasting higher defensive stats than Mienshao and Emboar, better speed than Conkeldurr and Emboar, and on top of it an Attack stat of 125 makes him viable, even later in the game. Not to mention that Sawk can get the great ability Sturdy, which makes sure it can't be knocked out in one hit when at full health. This gives him the chance to even battle Pokémon no other Fighting-type could or would.
N (Nacrene City): Sawk will give you the first taste of his power here. All of N's Pokémon get tossed aside effortlessly, including Pidove, which Sawk has the type disadvantage against. Double Kick, or if you have it already, Low Sweep deals with this battle easily.
Gym #2 - Lenora (Nacrene City, Normal-type): Normal gym leader right after catching Sawk? Yes please. Sawk's Double Kick or Low Sweep completely destroys Herdier. It may be able to get a Take Down in, but Sawk can take it. Be careful of Watchog, though. Normally Sawk shouldn't have trouble against it, but Hypnosis might be an issue, and Retaliate hits hard. Don't be afraid to heal or switch out Sawk.
Gym #3 - Bugsy (Castelia City, Bug-type): Sawk laughs at his Dwebble before Double Kicking it into oblivion. He does the job here better than most Water-types, since he resists all of Dwebble's attacks, and can one-shot it even though it has Sturdy, thanks to Double Kick. Whirlipede and Leavanny are risky. You could set up Work Ups against either one of them or against Dwebble, but Whirlipede knows Screech and Poison Tail, Dwebble can use Sand-Attack, and Leavanny has the critting Razor Leaf. Sawk would appreciate the help of a Fire- or Flying-type here.
Bianca (Castelia City): There's a Herdier there. Kick it to death. The problem is Intimidate. If that wasn't there, Sawk could have been able to sweep her entire team... that doesn't mean it's impossible, though. Retaliate works against Munna, preferably after a Work Up or two, and either Low Sweep or Double Kick can deal with her starter and the elemental monkey. Though, it's preferred to first deal with Herdier, then switch out when she goes for Munna, and take the field again after Munna is defeated. Then you get rid of his Attack drop as well, and can easily sweep what is left of her team.
Cheren (Route 4): This is pretty much the same story. Cheren only has Pidove and Liepard instead of Herdier and Munna, and his starter and the elemental monkey. This makes it even easier for Sawk to destroy his whole team. Watch out if his health gets in the orange, you don't want his starter or Pidove to get a lucky crit. Other than that, Sawk can and will sweep all of his Pokémon.
N (Nimbasa City): Sawk obliterates both Scraggy and Sandile. Darumaka may survive one hit, but Sawk can take one hit back and defeat it as well. Then the big threat comes: Sigilyph. It's preferred to switch Sawk as soon as possible, but if it has Sturdy and is at full health, he has a chance to defeat it. If you found the TM of Rock Tomb in Desert Resort, and you taught it to Sawk, you can use it to defeat Sigilyph in two hits. You will outspeed after the speed drop, but watch out for two things. The first is of course Rock Tomb's 80% accuracy. This means it will probably miss when you least want it to. Second thing is, you need Sturdy. Again. Even with Sturdy, you're not fully safe, since Sigilyph can outspeed and confuse you with Psybeam, forcing Sawk to kill himself. Sawk is able to battle the Sigilyph, but it's not encouraged at all.
Gym #4 - Elesa (Nimbasa City, Electric-type): Watch out for the winged squirrels of death. The same strategy you used against N's Sigilyph may work against her Emolga as well, but yet again, it's discouraged. Again, you need that Sturdy. Zebstrika is a lot easier, and will bite the dust fairly quick, thanks to you having found TM Dig on Route 4 and having used it on Sawk.
Cheren (Route 5): This man again? Liepard falls as easy as ever. Pignite and Pansear can only cry in agony as Dig knocks them out. Panpour, Pansage, Dewott and Servine fall to the powerful Brick Break, which Sawk probably knows by now. Tranquill is the only dangerous Pokémon here. As long as it doesn't crit with Air Cutter, Sawk takes it out in two attacks as well.
Gym #5 - Clay (Driftveil City, Ground-type): It would be sad if two of Clay's Ground-types have a dual type that makes them weak to Fighting-type moves. Krokorok and Excadrill fall quickly to Brick Break. Palpitoad can hit with Muddy Water, but Sawk is able to shrug that off and two-shot Palpitoad as well. Remember that, if you started the battle with Sawk, you should switch out before Excadrill comes, in order to remove that pesky Intimidate nerf; alternatively, use Work Up.
Bianca (Driftveil City): Elemental monkeys and starter are the same story as the battle against Cheren on Route 5. Herdier falls to Brick Break, but don't use Sawk against Musharna. Its bulk is way too high for any of Sawk's moves to damage it, and Psybeam hits hard.
N (Chargestone Cave): Well. This is easy. Brick Break defeats Ferroseed and Klink, Rock Tomb takes out Joltik. If you still have Double Kick, maybe use it against Boldore to bypass Sturdy. No worries if you don't have it anymore, it won't be able to hit you hard anyway.
Gym #6 - Skyla (Mistralton City, Flying-type): Sadly, you don't have access to TM Rock Slide yet, so avoid as much as you can. If you have Sturdy, you could try taking out Unfezant or Swoobat, but watch out for Rock Tomb's miss chance and Unfezant's Quick Attack. Swanna... no. Just stay away and let a Pokémon with an Electric-move do their wonders.
Cheren (Route 7): The time you could fully sweep Cheren is over. Liepard still proves to be no challenge for Sawk, and gets one-shotted. The evolved elemental monkeys may be too powerful, since Simisage now has Miracle Seed Seed Bomb and Simipour has Mystic Water Scald. The only one that wouldn't be too problematic is Simisear, who has 'only' Charcoal Flame Burst. Unfezant is pretty much impossible, unless you want to try that gimmick Rock Tomb strategy again. Could work, but try not to, since it's still really dangerous. As for the starters, Pignite now carries Heat Crash and Take Down, which still isn't too problematic. Sawk takes it down. Dewott boasts Water Pulse and Servine sports Leaf Blade and Leech Seed. The former isn't problematic either, but you'd do good if you let the latter to be handled by a Fire- or Flying-type. Again, Sawk will appreciate their support.
Gym #7 - Brycen (Icirrus City, Ice-type): Rest in peace, team Brycen. His team falls instantly to Brick Break, no exceptions.
Bianca (Route 8): Stoutland is now fully evolved, but no threat to Sawk. Take it out quickly. Simisage and Simipour are the same story as the Cheren battle on Route 7, as is Simisear. Only now they don't have held items. Stay away from Musharna for obvious reasons. Samurott's only attacking moves are Revenge, Aqua Jet and Slash, so you should be fine there. Still, be on your guard for the possible crits. Serperior has Coil and Leaf Blade, so get out of there and let something more appropriate handle it before it can get off too many Coil boosts; again, Fire- or Flying-type. Emboar is risky. Heat Crash's damage isn't to be trifled with, but Dig will two-shot it again. If you have Sturdy and are still at full health, there's nothing to be afraid of.
Gym #8 - Iris/Drayden (Opelucid City, Dragon-type): Take out Fraxure quickly with Brick Break. There's nothing to be afraid of there. Druddigon has decent defensive stats, Rough Skin (in Black), and powerful attacks, so using a special based Pokémon there is a good idea. Brick Break should KO Haxorus in three hits, but don't battle it unless you have Sturdy. If you have it, then there's no problem if it's setting up Dragon Dances. It won't KO you in one hit anyway. That is, if you are still at full health... otherwise, play your cards well: should Sawk fall, it is very likely that the rest of your team also will.
Cheren (Route 10): Liepard still falls as easily as ever, Unfezant is as impossible as ever. The elemental monkeys Simisage and Simipour are still the same, so hard, and so is Simisear, which is pretty possible. Serperior is the same as Bianca's on Route 8, except it carries Leftovers here. Get out quickly. Samurott knows Aqua Tail, so it's risky. Even Emboar is dangerous, as it carries Leftovers, and it will recover quite some damage in between Dig turns. It knows Flamethrower and Heat Crash, which hit both hard. Try to avoid battling it.
Elite Four Shauntal (Pokémon League, Ghost-type): Yeah, no. Cofagrigus is too bulky to hit, even with Payback or Rock Slide, and burns you with Will-O-Wisp. Golurk is too bulky as well, and it packs Curse. Chandelure is possible if Sawk knows Rock Slide, has Sturdy and is at full health. Sawk will outspeed Chandelure and two-shot it with Rock Slide, bulking Psychic thanks to Sturdy. Jellicent could be also possible to battle instead of Chandelure, using Payback instead. Yet again, have Sturdy to be on the safe side.
Elite Four Marshal (Pokémon League, Fighting-type): Throh may be risky due to Storm Throw. If you're sure you can two-shot it without using Close Combat to make Throh hit you even harder, then sure, go nuts. Marshal's own Sawk has no chance against yours. First use Brick Break, then finish it off with Close Combat. Conkeldurr is dangerous, but not impossible for Sturdy Sawk at full health, providing you haven't - or no longer have - any Defense dropdowns from Close Combat. Two Close Combats and it should be down, but again, consider what this means to your own defensive power. The same can be said about Mienshao, but there is a risk, namely that Mienshao may outspeed your Sawk. Best would be to take out either Throh and Sawk or Conkeldurr with him, and let him sit out the rest of the battle.
Elite Four Grimsley (Pokémon League, Dark-type): Kill everything using Brick Break or, for the stronger ones, Close Combat. Don't even question what you're doing. Kill everything.
Elite Four Caitlin (Pokémon League, Psychic-type): Uhhh. Reuniclus and Musharna are just too bulky to be fought with Sawk. Gothitelle is a big risk, even if Sawk has Sturdy and is at full health. Sigilyph is manageable though, at least if you have Rock Slide already...and of course, have Sturdy and be at full health.
Reshiram/Zekrom (N's Castle): Dig or Close Combat against Zekrom, Rock Slide against Reshiram. Switch when you're in danger, but normally Sawk should be able to take them both. There are better Pokémon for the job, though. Watch out for Reshiram's Extrasensory and Fusion Flare, and Zekrom's Zen Headbutt and Fusion Bolt.
N (N's Castle): Reshiram and Zekrom pack the same dangerous moves, except Reshiram now knows Reflect as well. Plus, you're going up against a full team. Try to not use Sawk here, as it is incredibly useful against some of N's other Pokémon. Vanilluxe, Klinklang and Zoroark all fall to Close Combat. Archeops is dangerous, but if you have Sturdy and are at full health, go nuts. You won't be able to one-shot Carracosta due to its Sturdy, so try using Brick Break first, and then finishing with Close Combat. Oh, and don't think about keeping Sawk in against Carracosta if its Defense is lowered due to previous Close Combats. Even if you have Sturdy and are at full health, Carracosta can use Aqua Jet to be faster.
Ghetsis (N's Castle): Obvious bad choice against Cofagrigus, do I even have to explain it? Bisharp and Bouffalant fall to Close Combat rather easily. Seismitoad is tricky. Try to not battle it, since you'll need all of Sawk's strength against Hydreigon. Same story with Eelektross. Although, if you really have nothing for it, then two-shot it with Close Combat. Again, only when Sturdy and full health. Hydreigon is threatening, but not so much for Sawk. Close Combat should finish it off in one hit.
Post-Game: Shauntal and Caitlin rematches are still bad choices, but there aren't many battles besides those in which Sawk has to fear for his life... again, as long as it has Sturdy.
A starting-out Sawk comes with Rock Smash and Leer, but a Sawk you just caught in the outside of Pinwheel Forest will pack Bide, which he learns at level 5, Focus Energy, learned at level 9, and Double Kick, learned at level 13, together with Leer. However, if you caught it at level 17, it will have Low Sweep instead of Leer. At level 21, Sawk learns Counter, which can be really useful against trainers that use Pokémon with powerful physical moves. Best used by a Sawk with Sturdy, for obvious reasons. At level 25, there's Karate Chop. No idea why it's only now there, since it's outclassed by both Double Kick and Low Sweep. Brick Break comes at level 29, and will be a great asset for Sawk. Then, at level 33, he learns Bulk Up, which he may use in any major battle to completely sweep enemy teams. Retaliate comes at level 37, but at this point, Sawk has way better moves to use. He learns Endure at level 41, which is pretty much worthless thanks to Sturdy. Even if you don't have Sturdy, not worth learning. Level 45, Quick Guard... meh. But then, at level 49, comes his greatest move, Close Combat. It will one-hit KO everything that is weak to it, and probably quite a few others as well. Reversal comes at level 53, but eh. It can be useful on Sturdy Sawk, as its base power will be 300, counting STAB, at 1 HP, but you put Sawk in great danger there. Not recommended.
As for the useful TMs. When you first catch Sawk, Work Up and Rock Smash are possibilities, implying that Sawk needs them. After the second Gym, you get Retaliate, which you can use to hit Pokémon that resist your Fighting-type moves. When you reach Route 4, pick up Dig, a very useful TM for Sawk. Not much later, in Desert Resort, you'll find Rock Tomb, another good coverage move. In Nimbasa City, you could buy Return to get raw power, but there won't be much benefit, since Brick Break will almost always outpower it. Then, on Route 16, TM Payback lies, which is a great help against Psychic- and Ghost-types... assuming you have Sturdy to shrug off their attacks in the first place. Bulldoze is received from Clay, but unless you have a Sawk with very low Speed, it's inferior to Dig. After you get Surf, a lot of good TMs become available for Sawk. The most notable ones are Low Sweep in Wellspring Cave, Poison Jab on Route 6 and Rock Slide, again in Wellspring Cave. Brick Break is available in Icirrus City, should you have made your Sawk forgot how to use it. In the postgame, there are the TMs for Bulk Up, Earthquake and Stone Edge which are valuable for your Fighting-type bro.
A welcomed item for Sawk would be a Black Belt, but it's only available in the Post-Game. Other possibilities are Soft Sand, Hard Stone, or a Fighting, Rock or Ground Gem.
Recommended moveset: Bulk Up, Close Combat, Rock Slide, Brick Break / Dig / Payback
Minimum stats are calculated with 0 EVs, IVs of 0, and a hindering nature, if applicable.
Maximum stats are calculated with 252 EVs, IVs of 31, and a helpful nature, if applicable.
What Nature do I want? Anything that strengthens Attack, preferably Adamant, but Lonely and Naughty could work as well. Jolly, Hasty and Naive as Speed boosters are good too.
Which Ability do I want? Sturdy, definitely. Inner Focus will hardly be used, and Sturdy became extremely useful in this generation.
How good is Sawk in a nuzlocke? Good, if only it wasn't for the low chance to get it. Sawk is a god-tier early game Pokémon, destroying everything on his path. There are a few threats that are best handled by fast Fighting-types (read as: Ghetsis's Hydreigon, half of N's team) which makes Sawk useful in the late game as well.