Its Mega is in NU, which is most definitely not a strong case for using it in OU. It's very passive, with a lot of its damage output coming from Toxic. This means that Poison and Steel types wall it with ease, and setup sweepers can take their time setting up against Audino, then obliterate it. It's also quite slow, and its attacking stats aren't the best.
You don't really have a reason to use Mega Audino in OU, it's too weak.
Source (Yes it's an NU analysis but the checks and counters still apply)
Hope I helped!