The Tepig line is available from the box sent to the player's house in Nuvema Town.
Ah, Tepig. The poor thing has perhaps the least love among starters, and its largely unwarranted. While it may have some bad matchups, on the whole it's a solid, hard-hitting Pokemon that's well worth the effort.
Bianca (Nuvema Town): Spam Tackle. Pray you don't get hit by crits.
Cheren (Nuvema Town): Blah blah Tackle spam.
N (Accumula Town): Try to be at least level 7 so you have access to Ember in order to ignore Growl debuffs. You shouldn't have any trouble; Purrloin's far from a powerhouse.
Bianca (Route 2): Lillipup can be dealt with using either Tackle or Ember and Snivy burns easy. Though you might want to switch if Tepig takes too many Leers, as it's pretty frail.
Cheren (Striaton City): Oshawott's obviously not something Tepig wants to deal with. Purrloin's no trouble though; even Assist-induced Water Gun is weak coming from those stats. Still, don't push your luck against it.
Gym #1 - Cress (Striaton City, Water-type): Best get to level 13 so Tepig can use Defense Curl to negate Work Up boosts-even then, be prepared to heal. Panpour's far too dangerous. You presumably have a Pansage. Use that instead.
Cheren (Route 3): Same as before; avoid Oshawott and kick Purrloin's butt.
N (Nacrene City): Pidove is dicey - crit Quick Attack will take out a good-size chunk of Tepig's health and that's without being debuffed by Leer. Timburr's easier than you'd expect due to Tepig's low weight making Timburr's Low Kick weak. However, it's best to stick to Tackle over Ember- Guts means if it ends up getting burned, you're boned. Keeping Tepig away from Tympole should be a no-brainer.
Gym #2 - Lenora (Nacrene City, Normal-type): After being Intimidated, about six hits of Arm Thrust will take care of the Herdier, though you'll want to use Defense Curl first to keep from being two-shotted by Take Down. That Defense Curl will also allow it to tank Watchog's initial Retaliate at the cost of half its health. After that, it's only a matter of firing off Arm Thrusts while healing as needed.
Gym #3 - Burgh (Castelia City, Bug-type): Firstly, if you haven't already done so, give Pignite the Eviolite. Though probably not needed for the gym, it's a good thing for Pignite's fragile self to have. Flame Charges will take down Whirlipede and Leavanny like they were nothing. Dwebble's quite a bit more durable, luckily its attacks are weak. (Arm Thrust is generally better for Dwebble than Flame Charge, unless you consistently roll low amounts of hits.)
Bianca (Castelia City): Flame Charges for Servine and Munna, Arm Thrusts for Herdier and Panpour. Even super-effective attacks are no problem to an Eviolited Pignite.
Cheren (Route 4): Avoid Dewott, Flame Charge or Arm Thrust everything else.
N (Nimbasa City): Arm Thrust your way through the Sandile and Scraggy and Arm Thrust/Return the Darumaka, but turn tail when Sigilyph shows up. That thing's enough of a challenge for Pokemon that aren't weak to it, let alone Pignite.
Gym #4 - Elesa (Nimbasa City, Electric-type): Eviolited Pignite can survive at least two hits from any attack including the Emolga pairs' Aerial Ace, though with Volt Switch antics in play soloing is a challenge. Doable, but have heals ready, especially Parlyz Heals; those squirrels have Static.
Cheren (Route 5): Liepard easily falls to an Arm Thrust or two. Pansear's no threat at all- the worst it can do is Yawn. Traquill, fortunately, is a physical attacker so even its Air Cutter is nothing to worry about- watch out for crits,though. Don't fight Dewott, for obvious reasons.
Gym #5 - Clay (Driftveil City, Ground-type): Krokorok can be beaten with some Arm Thrusty goodness(though beware of Swagger) but Palpitoad and Excadrill are packing too much power in their super-effective attacks. Excadrill won't even give Pignite a chance to hit before it goes down to Bulldoze.
Bianca (Driftveil City): Flame Charge/Heat Crash the Servine, Arm Thrust the Herdier, Return the Panpour and keep away from Musharna. Bulky Psychic-types are definately not Pignite's thing.
N (Chargestone Cave): Beat down the Boldore with Arm Thrust and burn all the rest. Poor N, this just isn't his day.
Gym #6 - Skyla (Mistralton City, Flying-type): Swoobat has Acrobatics, Unfezant has Air Slash and Swanna has a movepool full of nasty tricks. There is so much NOPE here it isn't even funny. Don't use your starter here.
Cheren (Route 7): Liepard dies to Arm Thrusts (and stiff breezes, let's be honest). Simisear has nothing worse than Fury Swipes and is frail, so go for it. Unfezant has a very-likely-to-crit Air Slash and Dewott has potentially-rain-boosted Water Pulse; gotta stay away from those.
Gym #7 - Brycen (Icirrus City, Ice-type): Hammer Arm everything. Laugh at Brycen's sad attempt at posing a threat.
Bianca (Route 8): Pound down the Stoutland with Hammer Arm. Heat Crash/Hammer Arm (depending on the weather) Serperior, though beware if you health is low as Coil-boosted Slam hurts quite a bit. Avoid Simipour and Musharna- Emboar's not a fan of STAB Psybeams and Scalds.
Gym #8 - Iris/Drayden (Opelucid City, Dragon-type): Two Hammer Arms each will take care of Fraxure and Druddigon and even a Dragon Dance boosted Dragon Tail won't kill Emboar without crits. Haxorus, on the other hand, may take three Hammer Arms. However, only Drayden's Haxorus with a boost from Rivalry and two Dragon Dances will OHKO Emboar with Dragon Tail; either way, make sure the rest of your team can handle things if dragged out, as switching Emboar back in against a Dragon Dance boosted dragon of any sort is pretty much suicidal.
Cheren (Route 10): Much the same as before. Liepard and Simisear are even easier now that you've replaced Arm Thrust for Hammer Arm. Unfezant's still not a thing for Emboar to fight and Dewott's now a Samurott with Aqua Tail for a redundantly higher level of lethality.
Elite Four Shauntal (Pokémon League, Ghost-type): Bad times all around. Cofagrigus and Chandelure both have Psychic, Jellicent has Surf and Brine and Golurk has Earthquake. Their shared immunity to Fighting moves is the final nail in the coffin.
Elite Four Marshal (Pokémon League, Fighting-type): Throh and Sawk are manageable with some heavy healing, but Conkeldurr and Mienshao are packing too much power for Emboar's low Defense to handle.
Elite Four Grimsley (Pokémon League, Dark-type): Hammer Arm your way through everything not named Krookodile (because it has Earthquake), though beware of Liepard and Bisharp if your health is low as they both have Aerial Ace.
Elite Four Caitlin (Pokémon League, Psychic-type): I sincerely hope I don't have to explain why sending Emboar in against a Psychic specialist is a bad idea. Just don't do it.
Reshiram/Zekrom (N's Castle): Reshiram has Extrasensory and Zekrom has Zen Headbutt. Seriously, just throw the Master Ball. That's what it's there for, and you need to catch the legendary to progress with the game anyway.
N (N's Castle): Reshiram/Zekrom still carry their respective Psychic attacks, so no. Carracosta has Aqua Jet and Waterfall and requires at least two attacks to knockout, so still no. Vanilluxe is a piece of cake, especially with Emboar resisting all its moves. Archeops is far too much; its Acrobatics will OHKO Emboar and then some. Zoroark's powerful, but it won't survive a Hammer Arm. Klinklang can be dealt with either Hammer Arm or Flamethrower; the former is preferred if Zoroark's still alive, as it might be hiding under Klinklang's appearance.
Ghetsis (N's Castle): The only thing here that Emboar can safely fight is Bisharp. Everything else is either a Psychic wielding Cofagrigus or can knock Emboar out in two moves while Emboar has no hope of OHKOing (barring lucky crits) or outspeeding twice.
Post-Game: If you do nuzlocke it, apply logic for the League rematches. As for the rest, apply common sense.
Tepig comes with the moves Tackle and Tail Whip. At level 7 Tepig learns Ember, though given the stat difference Tackle might actually be better. At level 9 comes Odor Sleuth which is crap. Level 13 brings Defense Curl, which might be handy as the Tepig line is low on Defense; it's the first stat-buffing moves the line can learn. Flame Charge appears at level 15 and two levels later, it gains Arm Thrust, which will be your main sources of attack for a while. Level 20's Smog is pathetic and level 23's Rollout may be tempting to pair with Defense Curl, but continuous moves are always a big risk in Nuzlockes. Level 28 has Take Down, not worth the recoil, especially with Return being available. At level 31 Heat Crash is learned, which in most cases is better than Flame Charge for damage. At level 36 it learns Assurance - handy for ghosts, but probably not worth a slot. At level 43 Flamethrower is acquired, and unless your Emboar leans very far to the physical side is a better choice than Heat Crash. Level 50 brings Head Smash -powerful, but terrible amount of accuracy and recoil.At levels 55 and 62 Roar and Flare Blitz are learned; the former is definitely not worth learning and the latter is awesome but comes too late. Also of note is that Emboar can relearn Hammer Arm. And by "can", I mean "definitely should, what are you doing, do it now!"
Emboar has a handful of choices in the TM department. Return is always a nice choice. Fire Blast is a possibility if you really like gambling, though Emboar may not survive if it misses. Scald may prove useful against fellow Fire-types and high-Defense Rock types. Gyro Ball may work well with its low Speed. Work Up is nice for a power boost. Bulldoze and Rock Slide are both useful for coverage.
Recommended moveset: Hammer Arm, Return, Flamethrower / Heat Crash / Fire Blast, Gyro Ball / Rock Slide / Bulldoze