Mega Audino is a huge threat in the current metagame in my opinion because it can beat Virizion and Heliolisk. Crodino is the most threatening set because it can set up on a lot of the current metagame leaving only strong steals and poisons to beat it. Wish/protect two attacks Mega Audino is also very good if you dont like having to rely on sleep talk rolls. Additionally, poison types are very rare due to mega Steelix being everywhere. Mega Lix is a problem however most people have found ways to handle it such as rocky helmet Xatu with heat wave or Mantine/Ludicolo.
Here are some calcs showcasing Mega Audino's bulk:
252 Atk Virizion Close Combat vs. 252 HP / 252+ Def Mega Audino: 93-111 (22.6 - 27%) -- 41.2% chance to 4HKO (doin nothin doin nothin)
+2 252 Atk Virizion Close Combat vs. 252 HP / 252+ Def Mega Audino: 186-220 (45.3 - 53.6%) -- 41% chance to 2HKO (you might have to pray that you are part of the 59% that isnt 2 hit KO'd)
252 SpA Life Orb Heliolisk Thunderbolt vs. 252 HP / 4 SpD Mega Audino: 138-164 (33.6 - 40%) -- guaranteed 3HKO (although this seems like it is doing a lot, Mega Audino can easily heal itself with rest and calm mind all over heliolisk in order to force it out)
The issue is that it's just far too easy to nab momentum with Heliolisk right now. Its Volt Switch is incredibly hard to outright stop, so most of your special walls will find themselves against highly unfavorable matchups nearly every time Heliolisk threatens a Pokemon. The Electric immune Pokemon in the tier all have difficulties switching into Heliolisk as well: the Ground-types greatly fear Surf and/or Grass Knot, while Lightningrod and Motor Drive mons take absolute loads from neutral hits. Even Lanturn, supposedly Heliolisk's best switch-in, cannot deal with Heliolisk by itself since Lanturn fails to do much back to Heliolisk and can get taken down by Hyper Voice before it even beats Helio; it usually must respond by Volt Switching to a faster teammate to check it. And that is usually against a standard moveset, but Heliolisk can very easily pack moves that lure and beat Pokemon that otherwise take its main attacks easily, such as Dark Pulse for Gourgeist and Focus Blast for Cradily, Audino, and Ferroseed, and considering the threat level posed by the standard set, you have no reason to believe it would drop one of its coverage moves for a luring attack until it is too late, and you leave yourself open to a large number of threats in the meta while Heliolisk's effectiveness very rarely suffers as a result (mostly because the teammates that appreciate its luring can conveniently make up for its unused coverage move). It's too good of a hit-and-run Pokemon (compounded by the fact that it has Dry Skin for added longevity, as well as discouraging the use of Water attacks), plus the incredible ease at which Heliolisk generates momentum while threatening a large variety of Pokemon makes it a suspect-worthy Pokemon.
Will pitch in my thoughts: Virizion often doesn't even need to set up to pose as a threat since its unboosted attacks can still do a decent number on NU already, it whizzes past a large majority of the tier, and even has great bulk and typing for an offensive Pokemon; this allows Virizion to put in good work even with the presence of revenge killers (which is by no means easy and usually requires a Scarf), which usually cannot afford to switch into most, if not any of Virizion's direct attacks, making them shaky checks. Furthermore, its ability to boost physically or specially elevates its threat level to frightening degrees, forcing people to run two or even more Virizion responses to keep it under control, which is made much more difficult since each of its main sets (SD Stone Edge, SD Zen Headbutt, CM) possess varying counters and checks.
Hey Espeon, it seems you are new here, and I am no pro to NU, but some suggestions. Like you have said, Volcarona is in BL, basically OU, but Mega Scizor is also OU, so I wouldn't bring it up here. Secondly, since Muk is more of a bulky Pokemon than a cleaner, Poison Jab is basically always preferred, as it along with Poison Touch gives a 60% chance to poison the opponent, as well as being reliable with 100% accuracy. Regarding your second moveslot, Mega Steelix is huge in this tier, and Fire Punch is doing nothing to it, and Rock Slide doesn't provide much, only giving you a super effective hit against Archeops, while other bug, flying, and fire types are hit hard by Poison Jab. I would suggest Earthquake, as it hits M-Camerupt for super effective damage, as well as bulky rock types and opposing Poison types immune to your poisoning. Priority is fine to secure double downs after poison damage, and finishing off a Typhlosion in Blaze. Fourth moveslot is best to be Ice Punch or if Mega Steelix is a super big threat to your team, you could try Focus Punch, hitting it hard on the switch, weakening it for another Pokemon to finish off. While Ice Punch hits ground types that threaten Muk with their STAB super effective EQs and such.
Except that it just Volt Switches out as they come in, and good luck blocking that Volt Switch when every Ground-type gets bopped by Surf or Grass Knot. Pretty much the only Heliolisk check that can block its Volt Switch is Lanturn, but it can't actually do much of anything back In spite of its frailty, it actually has a fair amount of opportunities to come in, mainly against Water-types thanks to Dry Skin, but also against Ghost-types like Missy and Rotom. It's best switch-ins are Grass-types, but even then stuff like Vileplume and Tangela get 2HKOed by Hyper Voice after SRs. Besides, it can just Volt Switch out to Typhlosion or Pyroar who just eat those plants alive, and your switch-ins to these guys are either Heliolisk-bait (Mantine, Prinplup) or some of its best checks like Lanturn or Hariyama (which get really weakened really quickly, especially with hazards). About priority, while it certainly stops a Heliolisk clean, it's primary goal is to punch holes and wallbreak, not sweep. Ban imo
