Last but not least, here are the C rank explanations. If you missed the first two posts, here are the links for the
S+A Rank explanations, and the
B Rank explanations. Keep in mind that while these mons can play a single role well enough to be considered viable, those roles on a bigger scale are typically played by mons in the S, A and B rankings. The mons in the C ranks may have something that makes them unique and for that reason, they are considered viable in OU.
C+ Rank
Avalugg is a physically defensive wall that also provides hazard removal via Rapid Spin. It can sponge hits from some physical wallbreakers like Dracozolt, Mamoswine, and Obstagoon, and then it can also avoid the 1HKO from set up sweepers including Swords Dance Excadrill, Aegislash, and Hawlucha. It can then proceed to KO them back with Avalanche or Earthquake. It also has reliable recovery in Recovery and can be immune to hazards thanks to Heavy-Duty Boots. However, despite being a physically defensive wall, it can get 2HKO'd by common Choice Band users, including Aegislash, Dracovish, and Tyranitar.
Barraskewda is only found on rain teams and is the fastest mon in the tier when Rain is active. It has decent coverage options in Liquidation + Close Combat + Psychic Fangs, but it is not terribly strong and is usually reserved as a cleaner rather than a wallbreaker. It is unable to boost its attack power, which can prevent it from being a bigger threat to bulkier teams. Rain not being in the best spot does have a negative effect on its viability.
Centiskorch runs a specially defensive set that enables it to switch into Fairy-types like Life Orb Clefable. Flash Fire grants it immunity to Fire-type attacks, and it relies on Rest + Sleep Talk to heal itself. Centiskorch can avoid being passive by utilizing Knock Off and Fire Lash, the latter of which has a 100% Defense drop rate, enabling it to deal more damage over time to an opponent who continues to stay in. Fire Lash allows Centiskorch to slowly, but surely pressure Calm Mind users like Hatterene.
Corsala-Galar is a surprisingly bulky mon that may be run on balance, semi-stall or stall teams. It runs a physically defensive set that is capable of walling common physical threats, such as Conkeldurr, Excadrill, and Hawlucha. While its bulk already allows it to handle those threats, Corsala-Galar has access to Strength Sap and Will-O-Wisp in order to lower the opponent's attack stat while healing up, and burn opponents respectively. It also provides Stealth Rock and can prevent Rapid Spin users from removing hazards thanks to its Ghost typing. It relies on Night Shade to attack, and while it is difficult to take down, it can be rather passive against most special attackers and can be taken advantage of by them fairly easily.
Flareon, like Centiskorch, runs a specially defensive set that is used to check Fairy-types. Flareon also relies on Flash Fire, and unlike Centiskorch, it can heal up teammates through Wish. Flareon can threaten special attackers with Flare Blitz, and it can use Yawn or Will-O-Wisp to status switch-ins like Seismitoad and Rotom-Heat. Yawn in particular can be nice as Flareon runs Protect, which can allow it to safely put the opponent to sleep.
Mew is typically used as a dual hazard setter on hyper offense teams. It gained Spikes this generation and can set up both Stealth Rock and Spikes while preventing the opponent from using Defog thanks to Taunt. Mew can also use Self-destruct to prevent the opponent from removing hazards, and it may also run Flare Blitz with Red Card to deal significant damage to Excadrill before phasing it out with Red Card, which also blocks the effect of Excadrill's Rapid Spin.
Mimikyu is back and runs the same set as it did last generation. Swords Dance with Shadow Claw and Play Rough alongside a Life Orb can grant Mimikyu respectable attacking power, while Shadow Sneak allows it to threaten faster targets, most notably Dragapult as it is the most used mon in OU. Disguise allows Mimikyu to absorb a hit at the cost of 12.5% of its health, and this can be very helpful for offensive teams that desire an emergency threat to fast sweepers like Hawlucha. That being said, Mimikyu does struggle with breaking past common physically defensive walls, such as Ferrothorn and Toxapex, the latter of which can also Haze away Mimikyu's boosts and threaten it with a Scald burn.
Snorlax is a Curse sweeper that is able to rely on its ability, Thick Fat, to help it set up against Fire and Ice-types in addition to special attackers in general. Body Slam + Darkest Lariat has near perfect coverage, with the former being capable of paralyzing opponents and the latter providing Snorlax the ability to defeat opposing Bulk Up and Curse users. Rest keeps Snorlax healthy and it can typically catch bulky offense teams by surprise. Snorlax will however, struggle against balance teams due to Toxapex having Haze, Hippowdon having Whirlwind, as well as balance having other ways to abuse Snorlax as it sleeps. This can also include Ferrothorn using Knock Off, Leech Seed, and Spikes.
Vaporeon is another bulky Water-type that can check Dracovish thanks to its ability, Water Absorb. Unlike the other bulky Water-types, it can provide Wish to heal up teammates while also providing Haze to prevent set up sweepers, such as Hatterene, from sweeping. Vaporeon may be found on stall teams for the aforementioned purposes it plays, and it faces competition from Seismitoad, Toxapex, Jellicent, Milotic, Pyukumuku and Quagsire as a bulky Water-type.
Xatu is an interesting pivot that is able to safely bring in teammates thanks to Teleport having negative priority. Magic Bounce prevents it from being directly statused by threats like Seismitoad, whom Xatu is also able to prevent from setting up Stealth Rock. Xatu did retain Roost, which allows it to stay healthy, and has some freedom with the last two slots. It may run Night Shade, Heat Wave, Air Slash, Thunder Wave, or Grass Knot in those last two slots. Heat Wave hits Steel-types, Air Slash is a generally good STAB move, Grass Knot to deal damage back to Seismitoad, and Thunder Wave to paralyze threats like Hydreigon and Tyranitar.
C Rank
Crawdaunt is a powerful wallbreaker that can wreak havoc against balance and stall teams. Adaptability alongside Knock Off and Liquidation severely limits defensive switch ins, especially when you consider how everything in this generation is prone to Knock Off. Crawdaunt runs a Choice Band set that also uses Close Combat to immediately KO Ferrothorn, and Aqua Jet to allow it to threaten faster threats like Dugtrio. While Crawdaunt is a fantastic breaker, it does suffer from having a low base speed stat of 55, which causes it to get outsped by Aegislash and most offensive mons in the tier.
Drednaw is a unique Swift Swim user that has access to Swords Dance, which can allow it to weaken or KO common water resists like Seismitoad, Toxapex and Ferrothorn. Drednaw also has the option to provide Stealth Rock at the cost of giving up Swords Dance. It has decent coverage with Stone Edge + Liquidation + Superpower, the latter of which can be used to 1HKO Ferrothorn after a Swords Dance. It can act as a wallbreaker on Rain, but it will typically fail to 1HKO most defensive threats after a Swords Dance. Despite that, significantly weakening water resists for teammates is valuable for Rain and it is something Drednaw can do decently well.
Pyukumuku can be used as a physically defensive wall on stall teams. It relies on Unaware to prevent set up sweepers from bypassing it, and It can use Soak + Toxic to status targets back. It did however, lose Block, which previously enabled it to trap threats. As a physically defensive Water-type, it faces competition from Seismitoad, Toxapex, Jellicent, Milotic, Vaporeon and Quagsire, the last of which is also an Unaware well.
Ribombee is a fast mon that can set up Sticky Web for hyper offense teams that utilize Sticky Web. Sticky Web teams are not as consistent as hyper offense teams that rely on dual screens, and for that reason, Ribombee is placed in C rank to establish that Sticky Web teams are viable, but not too consistent.
Umbreon, much like Sylveon and Flareon, runs a specially defensive set that not only provides defensive utility, but can also heal up teammates with Wish. Umbreon is a very sturdy Ghost resist that can switch into Dragapult, Specs Aegislash, and Gengar pretty comfortably. It is worth noting that physical Aegislash sets carrying Close Combat can threaten and KO Umbreon, which prevents it from fully handling Aegislash. Umbreon is a little limited in its final two slots, which could include Snarl, Foul Play, Yawn, or Screech. Snarl bypasses Substitute to deal damage and lower Hydreigon's special attack, Foul Play is a decent measure against physical attacker, Screech can lower defenses through Substitute in order for Foul Play to deal more damage, and Yawn can put the opposing mon to sleep. It faces competition from Mandibuzz, who can also provide Defog and is immune to hazards thanks to Heavy-Duty Boots.
C- Rank
Copperajah is an absolute monster under Trick Room, as it has incredible attacking power and coverage. Copperajah's ability, Heavy Metal, boosts the base power of Heavy Slam and Heat Crash and can help achieve notable KO's, such as Heat Crash 1HKO'ing specially defensive Corviknight with Stealth Rock. Power Whip provides Copperajah the ability to break through bulky waters, such as Seismitoad, while Earthquake can be used to help break through Toxapex. Copperajah can also be used as a Stealth Rock user, in part to it having good matchups against the common hazard removers in the tier. However, it is very slow and will typically have to give up a coverage move to run Stealth Rock.
Durant is on ok wallbreaker that uses a Choice Band set, as it no longer gets Hone Claws. Durant's base speed of 109 is excellent, allowing it to outspeed common offensive mons such as Hydreigon, Rotom-Heat, and Excadrill. Hustle alongside a Choice Band grants Durant solid raw power at the cost of lower accuracy. Durant can run First Impression, Iron Head, Superpower, Stone Edge, and it has additional coverage options in Thunder Fang and Stomping Tantrum. First Impression allows Durant to fire off a very powerful attack with priority that can hit any target regardless of their speed stat. Iron Head allows Durant to KO Fairy-types like Clefable, and will also be Durant's most reliable STAB move as First Impression only works on the first turn Durant is in. Superpower and Stomping Tantrum can hit Steel-types like Ferrothorn and Aegislash, while Stone Edge can hit Fire and Flying-types like Rotom-Heat and Gyarados. Thunder Fang can deal additional damage to Corviknight while also hitting Gyarados. While it can be a big threat, it does struggle with the negative effect of Hustle, as well as being a bit more prediction reliant than other choice item users. For example, when facing either Seismitoad + Clefable + Corviknight, Seismitoad can switch into Stone Edge, Iron head, and Thunder Fang, Clefable can switch into Superpower and First Impression, and Corviknight can switch into everything except Thunder Fang.
Flygon has a small niche as a Choice Scarf user who is immune to Spikes and resists Stealth Rock. It outspeeds every mon outside of weather mons and Hawlucha with Unburden activated. Flygon can act as a fast pivot and bring in teammates with U-turn, and it also has some decent coverage options to force out common offensive mons. Dragon Claw can force out Dragon-types like Dragapult, Hydreigon, Dracovish and Dracozolt. Rock Slide can force out Rotom-Heat, and Earthquake can hit Excadrill, Aegislash and Electric-types like Toxtricity. However, it is not fairly strong and as a Choice Scarf user, it faces competition from Rotom-Heat, Rotom-Wash, Rotom-Mow, Hydreigon and Ditto.
Haxorus can be an alright wallbreaker or sweeper thanks to Dragon Dance and Swords Dance. In addition to Outrage, it can run Earthquake and Iron Tail in order to hit Steel-types and Fairy-types respectively, and then it may also run Close Combat in order to get past Corviknight and immediately KO Ferrothorn. Base 97 speed is fairly nice, allowing it to outspeed other offensive mons such as Rotom-Heat, Excadrill and Obstagoon. Unfortunately, it does get outsped by Hydreigon, and Outrage sets struggle to get past Corviknight. Iron Tail, while powerful, does have accuracy issues and may cause Haxorus's sweep to come up short.
Polteageist is a decent Shell Smash user that can be found on hyper offense teams. In addition to Shell Smash, it runs Shadow Ball + Giga Drain + Stored Power. Shadow Ball is the STAB of choice and Giga Drain can be useful to keep Polteageist healthy while hitting some Dark-types, most notably Tyranitar. Stored Power can become very powerful thanks to Shell Smash along with Polteageist's ability, Weak Armor, which also boosts Polteageist's speed in order to allow it to outspeed the entire tier. While it is a dangerous special attacker, Polteageist generally struggles against Dark-types that aren't weak to Giga Drain, with Mandibuzz and Hydreigon being the most common threats to it. While Tyranitar is weak to Giga Drain, it can avoid the 1HKO and must be weakened a bit before hand.
Quagsire is a physically defensive wall that uses its ability, Unaware, to handle physical set up sweepers like Hawlucha and Bisharp. It can use Haze to prevent Mold Breaker Excadrill from breaking it, and it can status back with Scald or Toxic. Thanks to its typing and ability, it can shut down Rotom-Heat and manage against Dracozolt. As a physically defensive Water-type, it faces competition from Seismitoad, Toxapex, Jellicent, Milotic, Vaporeon and Pyukumuku.
Now that my trilogy of long posts is over, I hope you guys find this helpful or learn something from it. As always, anyone is free to ask questions or correct me if I incorrectly stated something above. Have a nice day, and I hope you all enjoy the first weekend of the new year.