→Extensions: You do need to catch Tornadus to obtain the dowsing extenion. I have found this because I personally reached Thundurus's orb requirement without catching Tornadus, and without getting the Dowsing extension until after catching Tornadus.
| Dowsing Extension
| Collect a total of 700 Dream Orbs
| This search extension reacts to Pokémon that are holding something.
| Slightly more pink Dream Clouds; items are more common than Pokémon