Cinccino C+ -> B
What is this cute fluffy thing doing in C+? In my opinion, it's one of the deadliest wallbreakers in the tier. Although its Attack is only 95, which isn't THAT high, but still acceptable (equivalent to Sneasel), with Cinccino's blazing fast Speed (also equivalent to Sneasel) and amazing movepool to complement its ability, Skill Link, should already place it above C-tier. Access to Bullet Seed, Rock Blast, and Tail Slap, all amazing 25 BP 5-Multi-Hit moves, gives Cinccino access to literally 125 BP moves at its disposal, with the bonus of breaking through Substitutes, Sturdy, and Focus Sashes. In fact, with STAB Tail Slap, it is able to OHKO a good number of frailer Pokemon in the tier.
252 Atk Life Orb Cinccino Tail Slap (5 hits) vs. 0 HP / 4 Def Sceptile: 310-370 (110.3 - 131.6%) -- guaranteed OHKO
252 Atk Life Orb Cinccino Tail Slap (5 hits) vs. 0 HP / 0 Def Tauros: 220-275 (75.6 - 94.5%) -- guaranteed 2HKO
That's not all; Cinccino's access to great coverage options in the form of Bullet Seed and Rock Blast help it tremendously to dispatch many common walls in the tier, something that Sneasel cannot boast.
252 Atk Life Orb Cinccino Bullet Seed (5 hits) vs. 248 HP / 176+ Def Jellicent: 285-350 (70.7 - 86.8%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Life Orb Cinccino Bullet Seed (5 hits) vs. 252 HP / 0 Def Eviolite Rhydon: 340-415 (82.1 - 100.2%) -- approx. 6.3% chance to OHKO
252 Atk Life Orb Cinccino Bullet Seed (5 hits) vs. 252 HP / 252+ Def Seismitoad: 520-625 (125.6 - 150.9%) -- guaranteed OHKO
252 Atk Life Orb Cinccino Bullet Seed (5 hits) vs. 204 HP / 248+ Def Vaporeon: 285-350 (63 - 77.4%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Life Orb Cinccino Rock Blast (5 hits) vs. 252 HP / 252+ Def Eviolite Golbat: 180-220 (50.8 - 62.1%) -- guaranteed 2HKO
252 Atk Life Orb Cinccino Rock Blast (5 hits) vs. 252 HP / 240 Def Xatu: 285-350 (85.3 - 104.7%) -- approx. 6.3% chance to OHKO
The fact that Cinccino is able to enjoy a 2HKO on many of the walls in the tier ensures that Cinccino can clean up easily after a match after they are weakened, or in fact weaken specific checks or counters for a teammate to sweep.
Additionally, while Life Orb is the preferred set for Cinccino in order to enjoy its amazing coverage, Cinccino can also opt to run a Choice Band set (similar to the Sneasel conundrum), which then also can actively function as a pivot thanks to Cinccino's access to U-Turn. Knock Off is also available for Cinccino to learn, in the event that the coverage is needed, and also to disrupt opponents by making them lose their item.
Although it is unfortunate that the main counter to Cinccino is one of the most common physical walls in the tier, Steelix, Cinccino users can opt to circumvent this using Z-Focus Blast:
4 SpA Cinccino All-Out Pummeling (190 BP) vs. 244 HP / 128 SpD Steelix: 230-272 (65.3 - 77.2%) -- guaranteed 2HKO after Leftovers recovery
This adds additional utility to Cinccino by allowing it to function as the perfect Steelix lure: as Steelix has no reliable recovery, it will be severely crippled for the rest of the match, potentially allowing a teammate to muscle past and sweep.
Finally, an additional option is to use Work Up Cinccino, allowing her to function as a late-game sweeper, once all faster threats and priority users are removed. I've also seen some users running King's Rock Cinccino, relying on that 41% flinch chance to clutch win, but that's annoying.
Alas, I recognize that one main flaw that gives me pause when using Cinccino is that her powerful STAB attack is not spammable - with a 85% Accuracy, equivalent to moves like Fire Blast. However, one should also note that a 125 BP Tail Slap is a boost compared to Fire Blast's 110 BP.
In summary, I would like to make the case for Cinccino being a powerful wallbreaker with amazing coverage, and has underrated versatility in being able to lure, pivot, sweep, or clean, depending on the user's needs.
Such a talented Pokemon should not be made to stay C Rank.