I was in Route 203 on Diamond, rematching trainers (yeah, I stil have no idea why I was rematching in a route full of weak trainers) when my Breloom's Toxic Orb poisoned it, and it was an annoyance outside of battle. I was out of Antidotes/Full Heals so I rushed back to Jubilife. On the way there I accidentally ran into some tall grass and boom! shiny Shinx.
I caught it with an ultra ball on the first turn. ;D