Rotom-W will almost never want to switch into Staraptor. CB Reckless Double-edge will always OHKO, and its Choice Scarf Returns will always 2HKO. Even its Choice Scarf CCs come dangerously close to 2HKOing Specially Defensive Rotom-W, and U-turn just means good match-ups. It can't switch into anything but BB(Actually it can't even switch into that, CB Reckless BB will always 2HKO SPD Rotom-W after rocks)
Jirachi is common, that's why I listed it as one of it's counters. Even still, CB Staraptor 2HKOs specially defensive Jirachi, and CM Rain Jirachi with CC 53% of the time after rocks.