Meditite and Medicham are both from the Hoenn region, but are found via the Sinnoh Sound in HGSS. Is there a reason for this other than "that's how they wanted it," and are there other examples of situations like this?
The Hoenn Sound attracts gen 3 Pokemon only. The Sinnoh Sound attracts gen 4 Pokemon and Meditite, though Meditite can be found wild in lots of places in Sinnoh. source I don't know why they decided to do this.