Here we go with the classic mixing of those seperate creation myths again.....
The residents of Hoenn don't know the legends of Sinnoh.
The residents of Sinnoh don't know the legends of Hoenn.
The legends are local, because the pokemon they are based on are local.
Really? The residents of Hoenn don't know the legends of Sinnoh?
Have you ever played Heartgold or Soulsilver?
If you have an event Arceus the Sinjoh ruins will be unlocked. This symbolizes
that the Johto people did know about the Sinnoh legends. So why not Hoenn?
Then right there on the SPOT, Arceus MAKES you an EGG CONTAINING either Dialga, Palkia or Giratina of your choice.
So therefore, you think that the people of Hoenn don't know about Sinnoh legends, but you're very wrong.