I love Alolan Muk, and am glad it got an OU analysis, but I'd like to suggest a different EV spread for this (hell, as well as for the main/listed EV spread). Dunno if this is the right place to post it, but the Alolan Muk analysis is already uploaded sooooo....
Muk-Alola @ Assault Vest
Ability: Poison Touch
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Rock Slide / Fire Blast / Shadow Sneak
- Gunk Shot
- Knock Off
- Pursuit
Honestly, Alolan Muk doesn't need any Attack investment to do what it needs to do, while dumping everything into making it as specially bulky as possible has noticeable benefits.
Let's do some comparison calcs.
With 240 Attack EVs and a positive nature:
240+ Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Gengar: 186-218 (71.2 - 83.5%) -- guaranteed 2HKO
240+ Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 4 Def Gengar: 446-528 (170.8 - 202.2%) -- guaranteed OHKO
(Other important targets below)
240+ Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 4 Def Tapu Lele: 187-222 (66.5 - 79%) -- guaranteed 2HKO
240+ Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Tapu Lele: 78-93 (27.7 - 33%) -- guaranteed 4HKO
240+ Atk Muk-Alola Knock Off vs. 0 HP / 4 Def Alakazam-Mega: 282-332 (112.3 - 132.2%) -- guaranteed OHKO
240+ Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Alakazam-Mega: 174-206 (69.3 - 82%) -- guaranteed 2HKO
240+ Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 0 Def Latios: 356-422 (119 - 141.1%) -- guaranteed OHKO
240+ Atk Muk-Alola Pursuit vs. 0 HP / 0 Def Latios: 150-176 (50.1 - 58.8%) -- guaranteed 2HKO
240+ Atk Muk-Alola Rock Slide vs. 0 HP / 4 Def Charizard-Mega-Y: 376-444 (126.5 - 149.4%) -- guaranteed OHKO
240+ Atk Muk-Alola Rock Slide vs. 0 HP / 0 Def Volcarona: 436-516 (140.1 - 165.9%) -- guaranteed OHKO
With 0 Attack EVs and a neutral nature:
0 Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 4 Def Gengar: 326-386 (124.9 - 147.8%) -- guaranteed OHKO
0 Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Gengar: 134-162 (51.3 - 62%) -- guaranteed 2HKO
0 Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 4 Def Tapu Lele: 138-163 (49.1 - 58%) -- 96.1% chance to 2HKO
0 Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Tapu Lele: 58-69 (20.6 - 24.5%) -- guaranteed 5HKO
0 Atk Muk-Alola Knock Off vs. 0 HP / 4 Def Alakazam-Mega: 206-246 (82 - 98%) -- guaranteed 2HKO
0 Atk Muk-Alola Pursuit vs. 0 HP / 4 Def Alakazam-Mega: 128-152 (50.9 - 60.5%) -- guaranteed 2HKO
0 Atk Muk-Alola Knock Off (97.5 BP) vs. 0 HP / 0 Def Latios: 264-312 (88.2 - 104.3%) -- 25% chance to OHKO
0 Atk Muk-Alola Pursuit vs. 0 HP / 0 Def Latios: 110-132 (36.7 - 44.1%) -- guaranteed 3HKO
0 Atk Muk-Alola Rock Slide vs. 0 HP / 4 Def Charizard-Mega-Y: 276-328 (92.9 - 110.4%) -- 56.3% chance to OHKO
0 Atk Muk-Alola Rock Slide vs. 0 HP / 0 Def Volcarona: 320-380 (102.8 - 122.1%) -- guaranteed OHKO
Alolan Muk achieves almost all the OHKOs/2HKOs it wants with no Attack investment, and is still able to Pursuit-trap what it needs to.
With 15 SpDef EVs and a neutral nature
252 SpA Choice Specs Gengar Focus Blast vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 129-152 (31.1 - 36.7%) -- 69.7% chance to 3HKO
252 SpA Choice Specs Gengar Focus Blast vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 129-152 (31.1 - 36.7%) -- 98.8% chance to 2HKO after Stealth Rock and 3 layers of Spikes
252+ SpA Choice Specs Tapu Lele Moonblast vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 169-199 (40.8 - 48%) -- guaranteed 3HKO
252+ SpA Choice Specs Tapu Lele Moonblast vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 169-199 (40.8 - 48%) -- 62.9% chance to 2HKO after Stealth Rock
+1 252 SpA Volcarona Inferno Overdrive (185 BP) vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 306-360 (73.9 - 86.9%) -- guaranteed 2HKO
+1 252 SpA Volcarona Hidden Power Ground vs. 252 HP / 16 SpD Assault Vest Muk-Alola: 134-158 (32.3 - 38.1%) -- 96% chance to 3HKO
252 SpA Charizard-Mega-Y Fire Blast vs. 252 HP / 16 SpD Assault Vest Muk-Alola in Sun: 207-244 (50 - 58.9%) -- guaranteed 2HKO
With 252 SpDef EVs and a positive nature
252 SpA Choice Specs Gengar Focus Blast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 95-112 (22.9 - 27%) -- 46.2% chance to 4HKO252 SpA Choice Specs Gengar Focus Blast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 95-112 (22.9 - 27%) -- guaranteed 3HKO after Stealth Rock and 3 layers of Spikes
252+ SpA Choice Specs Tapu Lele Moonblast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 123-145 (29.7 - 35%) -- 17.3% chance to 3HKO
252+ SpA Choice Specs Tapu Lele Moonblast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 123-145 (29.7 - 35%) -- guaranteed 3HKO after Stealth Rock
+1 252 SpA Volcarona Inferno Overdrive (185 BP) vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 223-264 (53.8 - 63.7%) -- guaranteed 2HKO
+1 252 SpA Volcarona Hidden Power Ground vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 98-116 (23.6 - 28%) -- 87% chance to 4HKO
+1 252 SpA Volcarona Fire Blast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola: 133-157 (32.1 - 37.9%) -- 94.9% chance to 3HKO
252 SpA Charizard-Mega-Y Fire Blast vs. 252 HP / 252+ SpD Assault Vest Muk-Alola in Sun: 153-180 (36.9 - 43.4%) -- guaranteed 3HKO
With max SpDef investment and a positive nature, Alolan Muk is able to handle threats like Specs Gengar and Tapu Lele even when hazards are up, something it is unable to do with the listed AV set more than once. Plus, with the investment, at full health you switch in on +1 Volcarona's Inferno OBERDRIBU and unless it gets a max roll on Fire Blast, you live and OHKO back with Rock Slide.
Just food for thought.