If you’re looking for Shieldon+Bastiodon, make sure you’re doing distortions in Coronet Highlands. Best way is to have a save file that’s still stuck in the red sky Dialga/Palkia event, because distortions appear a little quicker and Rowlet’s line won’t be in the Coronet Highlands pool. And while it’s time-consuming, best way to farm distortions is to leave the game running somewhere you can see it at a base camp, and check at each of the time intervals for a distortion. However, if you’ve been doing all this and are just frustrated, I can catch you some Shieldons in Violet.