Restaurant Le Nah is wimpy enough that as long as you're not trying to sketch an area-effect attack you should be fine, and it's over very quickly because all of the Pokemon they use (Pansear/sage/pour) are very, very weak. It's the easiest point to do it. If you're doing an AoE move, though, you're going to have to get creative or something.
Um...
A Triple Battle from Restaurant Le Yeah should work if you need to sketch Rock Slide or Boomburst or something. Put Smeargle on opposite ends of your team then shift the attack user into the middle to be sketched. That'd work.
There's not really any other place that you can use that has repeatable multi battles in which Sketched moves will be kept.