I found a shiny Smeargle and it kept calling for help, I didn't have any way to inflict a status and it only had 10 pp from False Swipe. I tried catching it in a Luxury Ball but it broke free and I was so close to using the Master Ball, but ultimately used an Ultra Ball.
That was the first time i've ever legitimately considered using the Master Ball, and I soft reset for 12 shiny portal legends in ORAS.