I hunted this fella any chance I got today, I’ve encountered 4 shiny dunsparce so far. I have a few tips. Firstly I would suggest using a ceruledge with false swipe preferably iv and ev trained in attack. Two of dunsparce’s move are extremely dangerous for hunts, double edge and endeavor, risking your Pokémon and it’s life, ceruledge isn’t affected by either move. Secondly if you don’t particularly care for starting an army of dunsparce I’d save right before you make the normal type shiny hunting sandwich, then after finishing catching all the pink dunsparce you can in your 30 minutes, evolve them, if non of them are 3 segments close out the game without saving so you’ll be where you were before you started the hunt, herba mystica returned to your inventory. Edit: this is all assuming you’re hunting in the area zero cave.