Focus Sash fixes this, and if it switches on something it can take, eg, a Sacred Sword from Kartana, it can probably OHKO back. I do take your point about Mudsdale sucking, however, but I was focusing more on the ability than the mon. Eviolite Mudbray let’s GOMudsdale is very mediocre in general, and can easily be worn down using hazards or status. It's also pretty easy to OHKO and avoid triggering Stamina in general. You can also just set up on it, allowing your pokemon to sweep.