Agreed on Mimikyu. If someone where to try this strategy, Mega Lopunny would be the best candidate - Scrappy with Fighting/Normal is perfect neutral coverage, Drain Punch can be taken over HJK to still hit hard while recovering HP lost from Belly Drum, and it has priority with Quick Attack or further coverage. At the +6 you can pick off even bulky targets with neutral hits even with the 75 base power Drain Punch, and frail fast mons with the priority if you were worried about a scarf:I think there is merit to this strategy (after all, Aurora Veil teams in lower tiers dedicate 2 mons to setting it up), but I don't think Mimiyku specifically is a good user of it. It already has two options for boosting moves (Swords Dance and Z-Splash), and the low Base Power of its moves combined with its mediocre Attack stat means that it's not hitting hard even at +6. Azumarill doesn't have Disguise, but it hits quite a bit harder, can more easily get a free turn as it forces out mons so easily, and doesn't need Snorlax's help Your opponents also made some bad plays, sometimes saccing mons for no reason even after you revealed Copycat.
There's several other candidates for this, both in OU and in other tiers. I'd recommend you try them too, and see which works best.
+6 252 Atk Lopunny-Mega Drain Punch vs. 248 HP / 104+ Def Celesteela: 408-480 (102.7 - 120.9%) -- guaranteed OHKO
+6 252 Atk Lopunny-Mega Drain Punch vs. 188 HP / 0 Def Zygarde: 430-507 (106.4 - 125.4%) -- guaranteed OHKO
+6 252 Atk Lopunny-Mega Quick Attack vs. 0 HP / 0 Def Tapu Koko: 310-366 (110.3 - 130.2%) -- guaranteed OHKO
+6 252 Atk Lopunny-Mega Quick Attack vs. 0 HP / 4 Def Greninja-Ash: 373-439 (130.8 - 154%) -- guaranteed OHKO
Still a bit of a screwball and situational strategy that I don't think is really all that viable, and unless the opponent is asleep you're vulnerable on the BD or set-up turn, but M-Lop does have an insane combo of speed, power and neutral coverage if someone pulled it off.