Carbink may only be found in Reflection Cave, in both games.
The "Little Diancie" of the Kalos region! Carbink's typing is unique, for better or worse, and its stats even more so. It will never hit very hard, but it can take hits like few other Pokémon can do, and on both sides of the offensive spectrum. Since its base HP stat is so much lower compared to the two defenses, players will get the most from Carbink by at least EV training it in HP; maxing out the stat makes a great difference, and dramatically improves the usability of this Pokémon - which is already great on its own, but can be even better if raised the right way. Carbink's great stats and dual screen support also make it great for setups, providing Calm Mind later down the road, towards the endgame. While Carbink is definitely not the right species to use for players who like things that hit hard and win fast, it can be of great help against enemies that many other Pokémon are incapable of handling.
Rival (Tower of Mastery): Carbink can profit of Meowstic to set up Stealth Rock and then wear it down with Rock Tomb or, if already available, Ancient Power. It also works wonders against Absol, which barely scratches Carbink with just about any of its moves. However, aside from Braixen, Carbink is no good against Quilladin or Frogadier, both of which can nearly 2HKO with their respective STAB moves.
Gym #3 - Korrina (Shalour City, Fighting-type): Carbink can do great work in this gym, but with patience and possibly some healing items. Machoke and Hawlucha can both only kill Carbink from full health with a critical Power-Up Punch at +6 Attack, and only if Carbink's Defense is much lower than average. Mienfoo offers good Stealth Rock setup material, as well. Carbink's strongest offensive move in this fight is Nature Power, available via TM, which will be converted to Tri Attack.
Rival (Coumarine City): This matchup is an exact repeat of the Tower of Mastery one, only at higher levels. As such, it should be handled the same way: Carbink can set up Stealth Rock against Meowstic before wearing it down with its best move, and then take on Absol. Only Braixen of all the starters should be fought, however.
Gym #4 - Ramos (Coumarine City, Grass-type): Carbink is surprisingly good for this matchup. Since Grass Knot is the only damaging Grass move that Ramos' Pokémon have, which has a measly base power of 20 (not counting STAB and weakness) against Carbink's feather weight, Carbink actually takes very little damage from it. Jumpluff and Weepinbell will go down without problems, although Gogoat's Bulldoze will make it need some helping.
Aliana (Kalos Power Plant): Carbink has little to fear from this matchup, since Mightyena's only damaging move is Assurance. Swagger is also relatively non-threatening unless Mightyena manages to boost Carbink's Attack to the max, at which point the self-induced confusion damage will actually hurt; however, at that point, Carbink can flat out destroy Mightyena with a physical move.
Gym #5 - Clemont (Lumiose City, Electric-type): Emolga cannot deal much damage to Carbink, but it will most certainly use Volt Switch to have Magneton take its place, and Magneton's Mirror Shot is a clean OHKO. Since Magneton can set up Electric Terrain to power up Thunderbolt, it is best to start off with a Pokémon that can dispose of either Emolga or Magneton, and have Carbink sub in only after at least one Pokémon is defeated (and never in front of Magneton, in either case). Carbink can take down Emolga with Rock Tomb or Ancient Power and do the same against Heliolisk, or use Return for greater damage, though beware that the Heliolisk fight will require Carbink be occasionally healed; Thunderbolt can deal over 50% under the effects of Electric Terrain.
Rival (Route 14): Carbink still owns at least two thirds of this team effortlessly. Meowstic and Absol are never really threatening to it, not even after the addition of Swords Dance to Absol's arsenal: it can at best 2HKO after maxing out its Attack, and even critical hits cannot kill Carbink. Naturally, both Chesnaught and Greninja should be considered categorically off limits, as they now have the stats and moves to actually threaten the rock.
Gym #6 - Valerie (Laverre City, Fairy-type): Carbink fares well against this gym. Mawile has no Steel STAB, and only Dark moves to hit with, so Carbink will not take much damage from it; it would probably be best to fight it with another Pokémon, though, because Carbink also will not be dealing much damage. Mr. Mime and Sylveon can both be defeated with the usual amount of patience, preferably relying on physical moves, as their special bulk is remarkable; Stealth Rock against Mawile provides good help with chip damage.
Celosia and Bryony (Poké Ball Factory, tag battle with rival): While neither Manectric nor Liepard are specifically dangerous for Carbink, Liepard should preferably be disposed of quickly to prevent it from using Hone Claws repeatedly; if both of them gang up on Carbink, a nasty critical hit from half health may bring it in KO range with the other Pokémon finishing the job. Once Liepard is gone or nearly gone, Manectric can barely tickle Carbink.
Mable (Frost Cavern): Rock Tomb can 2-3HKO Houndoom, whose moves can barely even damage Carbink.
Rival (Anistar City): Meowstic and Absol continue to represent no threat for Carbink, even more so now that Carbink has access to Dazzling Gleam. Only Vaporeon of the possible Eeveelutions gives Carbink a hard time, with Muddy Water; Jolteon and Flareon are relatively easy to beat, especially if Carbink has had the chance to set up Stealth Rock before, which will chip away a significant portion of Flareon's health. Delphox has Psychic now, but can only 3HKO; Carbink can still exchange blows with it and eventually come out on top. Chesnaught and Greninja must still be avoided.
Gym #7 - Olympia (Anistar City, Psychic-type): Power Gem can 2HKO Sigilyph easily, unless it puts up Light Screen, which is still not an issue: it does not know Calm Mind, and its Psychic can only do so much to Carbink. However, neither Slowking nor Meowstic should be fought: while their own Psychic is a 3-4HKO by default, Carbink takes way too long to deal significant damage to them, and giving them free turns to use Calm Mind is not a wise idea. Use a fast physical hitter to deal with them.
Lysandre battle #1 (Lysandre Labs): Dazzling Gleam makes history of Mienfoo and Murkrow, and Murkrow's Steel Wing cannot kill Carbink even with a critical hit. Power Gem disposes of Pyroar, who only has not very effective moves to hit Carbink with. Gyarados' Iron Head, however, is another story; it needs to be handled by a better suited counter.
Aliana (Lysandre Labs): Dazzling Gleam, or even Moonblast if Carbink already has it, is all that is needed to turn this matchup into a cakewalk. Even Druddigon's Surf deals pitiful damage.
Celosia (Lysandre Labs): Carbink should approach this battle by setting up Stealth Rock first, and possibly also Reflect. Defeating Manectric is not difficult, but Drapion's Acupressure can turn against entire teams very fast with the appropriate boosts. Carbink's Moonblast is a near-certain 3HKO after Stealth Rock damage, not counting potential Special Defense boosts, and Drapion's best move - Poison Jab - can only deal about half even at +6 Attack, if Reflect is up on Carbink's side. Naturally, a critical hit will kill from +4 onwards, but the combination of Stealth Rock and Moonblast - possibly supported even by the Rocky Helmet - makes this scenario exceedingly unlikely to happen.
Bryony (Lysandre Labs): Moonblast makes short work of Liepard, but Bisharp has STAB Iron Head. Pick a better Pokémon to fight it.
Mable (Lysandre Labs): Neither Houndoom nor Weavile represent a threat for Carbink whatsoever, and it can 2HKO Houndoom with Power Gem as well as 3HKO Weavile with Moonblast, or 3HKO with Dazzling Gleam. Dazzling Gleam also becomes an OHKO if Stealth Rock has been previously set up.
Xerosic (Lysandre Labs): Steel Wing is only a 2HKO against Carbink, but so are Power Gem and Stone Edge, and Carbink is slower; it will not win the matchup. On the upside, Moonblast 2HKOs Malamar, long before its Contrary Superpower boosts may even become a problem.
Lysandre battle #2 (Team Flare Secret HQ): Moonblast is great against Mienshao and Honchkrow, but Honchkrow's critical Steel Wing can kill Carbink; this risk should not be taken if there are safer options available. Pyroar is easy with any Rock move, and Gyarados is still off limits, due to Iron Head.
Xerneas (Team Flare Secret HQ, X only): Carbink is not in luck; Xerneas' Moonblast can 2HKO it, and Carbink's own only does about half as much damage. In addition, Xerneas' Geomancy can become a serious threat for the entire team, thus Carbink should not fight here.
Yveltal (Team Flare Secret HQ, Y only): Yveltal's moves deal pitiful damage to Carbink, whose Moonblast is a 3HKO without Snarl thrown into the mix; even if Yveltal does spam Snarl, it will only be annoying at best. Carbink has this matchup in the bag.
Lysandre battle #3 (Team Flare Secret HQ): Mienshao and Pyroar are still easy to fight and cannot threaten Carbink much. Honchkrow, as before, can OHKO Carbink with a critical Steel Wing, and should therefore be avoided unless there are no other options; in that case, Moonblast will KO only after Stealth Rock has been set up. Mega Gyarados' Iron Head is even worse than regular Gyarados', so prepare a proper counter for it.
Professor Sycamore (Couriway Town): Carbink is 2HKOed by Venusaur's Petal Dance, leaving little wiggle room for Calm Mind setups. They are, however, possible against Charizard, which only knows moves that Carbink resists. Although Charizard is simply OHKOed by Power Gem, a full +6 Calm Mind setup will allow Carbink to also defeat the otherwise impossible Blastoise, which 2-3HKOs with Aqua Tail; if its Special Attack is maxed out, Carbink has good chances of OHKOing it with Moonblast.
Shauna (Route 19): Delcatty is Carbink's setup material. After +4 or higher achieved through Calm Mind, Carbink can OHKO Delcatty, Goodra, Chesnaught and Greninja with Moonblast, and Delphox with Power Gem. Carbink also needs extra carefulness against the first two starters, however, as Water Shuriken and Seed Bomb are respective 2HKOs (Water Shuriken from four hits upwards); if Carbink is to fight against them, it should both have the setups ready and be healed beforehand.
Tierno (Route 19): Carbink can set up Calm Minds against Talonflame until it hits +4 or more. Then, Power Gem will OHKO Talonflame and Roserade, and Moonblast will take care of Crawdaunt. In order to win against Crawdaunt, Carbink needs to either outspeed or be close to full health, because Crawdaunt's Crabhammer deals up to about 80%. Roserade's Petal Dance, instead, will not be scary after the many Special Defense boosts.
Trevor (Route 19): In order to win, Carbink will need all the Calm Minds it can get. Raichu's Thunderbolt is not a big issue, as it 4-5HKOs normally, and the damage will quickly lessen as the setup continues; Carbink should not off Raichu until it hits +6. It can then OHKO Raichu with Moonblast and Aerodactyl with Power Gem. At either point during the sweep, it should be healed before Florges comes; its Energy Ball is normally a 3HKO, and even with a maxed out Special Attack, Carbink can 2HKO at best. Barring any critical hits, however, Calm Mind will do the work and reduce the damage Carbink takes.
Gym #8 - Wulfric (Snowbelle City, Ice-type): Carbink should not fight Abomasnow or Cryogonal, both of which can 2HKO it with Energy Ball and Flash Cannon respectively, even after a Calm Mind. Instead, it can defeat Avalugg without problems, as its Gyro Ball is not an OHKO even with a critical hit and Power Gem 2HKOs it.
Rival (Victory Road): Since Meowstic's Psychic deals relatively trivial damage, Carbink should set up Calm Minds against it and then sweep the rival's team. A full +6 allows Carbink to either OHKO or 2HKO all of the rival's team; Absol and Altaria would be easy for Carbink either way, and Jolteon and Flareon would be doable without setups as well, but Vaporeon's Muddy Water is too strong for an unboosted Special Defense stat with Carbink's weakness to Water. The setup is also crucial to beat Greninja, which would otherwise KO Carbink in two turns with Water Shuriken, provided a high enough damage roll and 4-5 hits each.
Elite Four Wikstrom (Pokémon League, Ironworks Chamber, Steel-type): This matchup is very bad for Carbink, leaving it with only not very effective moves to hit with, and no room to Calm Mind. It should not participate in this battle.
Elite Four Malva (Pokémon League, Blazing Chamber, Fire-type): Pyroar's moves have a low enough damage output that Carbink can set up without a worry. At +2 or +3 Calm Minds, depending on Carbink's Special Attack, Power Gem is guaranteed to OHKO all of Malva's team.
Elite Four Drasna (Pokémon League, Dragonmark Chamber, Dragon-type): Carbink should avoid Dragalge, which can outdamage with Surf. It can then profit of Druddigon to use Calm Mind at will, thanks to its immunity to Dragon Tail; at +3 Special Attack, Moonblast is guaranteed to OHKO all three of the remaining Pokémon.
Elite Four Siebold (Pokémon League, Flood Chamber, Water-type): Carbink should not fight against Siebold, as all of his Pokémon can outspeed it and 2HKO with their respective Water STABs.
Champion Diantha (Pokémon League, Radiant Chamber): Hawlucha is good setup material for Carbink; at +2 Calm Minds, it can OHKO with Moonblast, and the same move will also OHKO Tyrantrum after Carbink survives an Earthquake or a Head Smash (even critical hits cannot kill from full health). Aurorus' Blizzard is as powerful as Carbink's Power Gem without any Calm Minds up, so even if Carbink was unable to set up, it will still triumph against Aurorus; with a +2, it will 2HKO, and can OHKO starting at +4. However, if Carbink also wants to face Gourgeist, it will need a minimum of +5 to OHKO, as Gourgeist will otherwise 2-3HKO with Seed Bomb. Goodra's Muddy Water is also unsurmountable without a prior setup, but at +4 or higher Carbink will 2HKO just fine, reaching OHKO range at +5 or +6, depending on its Special Attack stat. A setup of +4 or higher will also allow Carbink to 2HKO Mega Gardevoir, whose moves are only 2HKOs in Carbink's natural state, and deal next to no damage with Calm Mind boosts, achieving a potential Diantha solo if the right conditions are met.
Post-Game: Anything that reeks Steel should be kept well away from Carbink, but other than that, there are not many hits it cannot take.
Carbink's initial moveset is Sharpen, Smack Down, Reflect and Stealth Rock. It appears evident, in case the stats were not telling enough, that it works in an eminently defensive way. Guard Split, at level 27, is only going to hurt it; leave it be. Ancient Power, at level 31, may be an option over the Rock Tomb TM depending on Carbink's nature and stats. Flail, at level 35, is an interesting option if used with much prediction, but not typically better than its support moves and STABs. Skill Swap comes at level 40, but is generally not a great use of a move slot, since Clear Body is not a bad ability. Finally, at level 46, it learns Power Gem; unless your Carbink is Adamant, you will want this move on its set, particularly after obtaining the Calm Mind TM. Stone Edge comes at level 49, and may be an alternative to Power Gem, once again depending on Carbink's stats. Moonblast, at level 50, is the long awaited Fairy STAB; take it. The last two moves are optional: Light Screen, at level 60, complements Carbink's movepool nicely in the event of a support set but will not find much room for a setup one; Safeguard, at level 70, is less useful than Light Screen and has already been available for a relatively long time at this point.
Carbink's TM pool is quite good. Calm Mind is a great option to run setups, and it can either be supported by a fully offensive set comprising Dazzling Gleam (useful until Moonblast is learned), Power Gem and Psychic, or be kept alongside other support moves as a gimmick that allows Carbink to either stay in and fight, or bail out and leave presents for its teammates. Reflect and Light Screen both work very well for support purposes, but the TMs are exclusive to the postgame, so the moves must be relearned through the Move Reminder if forgotten; Sandstorm is more adequate for sets that also include Toxic, as a Carbink running Sandstorm will generally want to stay in the battlefield as long as possible to fully benefit from the 50% Special Defense boost. Trick Room can give it an edge against fast foes, as well.
Fighting-types: The best possible counters for Steel-types are Fighting-types, if on the same team as Carbink; fellow Steel-types only provide a resistance and, like Fire-types, they are also weak to Ground, a weakness that would overlap with Carbink's own. Therefore, Fighting-types are recommended as the resident Steel-type terminators.
Grass-types: Grass-types cover Carbink's Ground, Water and Grass weaknesses in one fell swoop; they are, hands down, the best possible types to complement Carbink after whatever on the team can help against its glaring Steel weakness. Grass-types with a secondary typing may work better than pure Grass-types, as they have more coverage to work with against their own Grass cohorts; on the other hand, they might also lose one of their relevant resistances.
Fast hitters: Carbink is slow without Trick Room, and Trick Room can only be used proficiently in some matchups. It is recommended to have a glass cannon, or similar Pokémon, on the same team as Carbink, so that the fast hitter spot is covered in matcuhps where attacking first is key.
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? Carbink works best with natures that lower Speed and boost one of its defenses, so Relaxed and Sassy are the preferred options. Lowering its Attack will not matter in the long run, but special coverage is not easy to come by, so it will deal even less damage in the first half of the game if its nature is Bold or Calm; later on, it will compensate. Quiet and Modest are also perfectly workable.
How good is Carbink in a Nuzlocke? Very good if used well. Its weaknesses are largely not crippling, exception made for the Steel one; aside from unexpected Steel coverage, Carbink has little to fear from roaming in Kalos. Its usability is higher than one would expect from the raw stats, and it can be flung at nearly anything without Steel coverage without even being at risk of dying. It takes time to wear its enemies down, but few of them can stand up against it.
Weaknesses: Ground, Water, Grass, Steel (x4)
Resistances: Normal, Flying, Bug, Fire, Dark
Neutralities: Fighting, Poison, Rock, Ghost, Electric, Psychic, Ice, Fairy