First off, replace Return with Knock Off to hit Ghost types plus it's just a good move this gen.
252 Atk Choice Band Cinccino Bullet Seed (5 hits) vs. 248 HP / 252+ Def Tyranitar: 220-270 (54.5 - 66.9%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Choice Band Cinccino Knock Off (97.5 BP) vs. 252 HP / 0 Def Aegislash-Shield: 180-214 (55.5 - 66%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Choice Band Cinccino Tail Slap (5 hits) vs. 4 HP / 252+ Def Blissey: 450-530 (69 - 81.2%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Choice Band Cinccino Tail Slap (5 hits) vs. 4 HP / 252+ Def Eviolite Chansey: 335-395 (52.1 - 61.5%) -- guaranteed 2HKO
252 Atk Choice Band Cinccino Rock Blast (5 hits) vs. 0 HP / 4 Def Multiscale Dragonite: 175-210 (54.1 - 65%) -- guaranteed 2HKO, though the first breaks Multiscale so it's an almost guaranteed OHKO.
252 Atk Choice Band Cinccino Rock Blast (5 hits) vs. 248 HP / 0 Def Togekiss: 350-420 (93.8 - 112.6%) -- approx. 81.3% chance
252 Atk Choice Band Cinccino Tail Slap (5 hits) vs. 252 HP / 252+ Def Clefable: 215-260 (54.5 - 65.9%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Choice Band Cinccino Bullet Seed (5 hits) vs. 252 HP / 252+ Def Quagsire: 540-640 (137 - 162.4%) -- guaranteed OHKO
252 Atk Choice Bandn Cinccino Rock Blast (5 hits) vs. 252 HP / 252+ Def Skarmory: 95-115 (28.4 - 34.4%) -- approx. 99.7% chance to 4HKO after Leftovers recovery
252 Atk Choice Band Cinccino Tail Slap (5 hits) vs. 252 HP / 88+ Def Ferrothorn: 80-100 (22.7 - 28.4%) -- possible 5HKO after Leftovers recovery
252 Atk Choice Band Cinccino Rock Blast (5 hits) vs. 252 HP / 252+ Def Forretress: 95-115 (26.8 - 32.4%) -- guaranteed 4HKO
252 Atk Choice Band Cinccino Rock Blast (5 hits) vs. 248 HP / 0 Def Heatran: 160-190 (41.5 - 49.3%) -- guaranteed 3HKO after Leftovers recovery
252 Atk Choice Band Cinccino Tail Slap (5 hits) vs. 252 HP / 252+ Def Sylveon: 240-285 (60.9 - 72.3%) -- guaranteed 2HKO after Leftovers recovery
Hope this helped :)