Offensive Threats (

,

,

and

)
160+ Atk Decidueye-Hisui Triple Arrows vs. 0 HP / 0 Def Krookodile: 326-386 (98.4 - 116.6%) -- 87.5% chance to OHKO
252 Atk Krookodile Gunk Shot vs. 240 HP / 100 Def Decidueye-Hisui: 260-306 (68.9 - 81.1%) -- Guaranteed 2HKO
160+ Atk Decidueye-Hisui Leaf Blade vs. 0 HP / 0 Def Mimikyu: 163-193 (64.9 - 76.8%) -- guaranteed 2HKO (if Disguise is already broken and there is any chip, this can often clean up)
252+ Atk Life Orb Mimikyu Play Rough vs. 240 HP / 100 Def Decidueye-Hisui: 351-413 (93.1 - 109.5%) -- 56.3% chance to OHKO (not enough bulk to guaranteed live, but a close to 50/50 against a mon you will likely switch out of is okay with me)
160+ Atk Decidueye-Hisui Triple Arrows vs. 0 HP / 0 Def Maushold: 362-428 (125.2 - 148%) -- guaranteed OHKO
252 Atk Technician Maushold Population Bomb (10 hits) vs. 240 HP / 100 Def Decidueye-Hisui: 370-450 (98.1 - 119.3%) -- approx. 87.5% chance to OHKO (9 hits is roughly 25% I believe)
160+ Atk Decidueye-Hisui Triple Arrows vs. 0 HP / 0 Def Iron Jugulis: 153-181 (46.5 - 55%) -- 65.6% chance to 2HKO
252 SpA Iron Jugulis Hurricane vs. 240 HP / 0 SpD Tera Water Decidueye-Hisui: 180-213 (47.7 - 56.4%) -- 85.2% chance to 2HKO (not ideal to stay in and Tera against Jugs, but viable if needed because Hurricane into Dark Pulse doesn't 2HKO after Tera)