That is impossible as far as i know she always will say "Sorry past this point is off-limits."
It's Manaphy and you can get its Pokedex data from a book at the Pokemon mansion below Hearthome.
She is in the house right next to the Pokemon Center in Hearthome City.
go to hearthome city
It's not an old lady who knows about Manaphy which is how you get its data in your Sinnoh Dex but rather a book that can be found in Mr. Backlot's Pokémon Mansion which is south of Hearthome City.
yes, it is a mansion Pokemon well you can also breed it at the daycare with a ditto, then hatch the egg
if you mean the owner he's on the left path and into the first room with a maid standing next to it.
the gym is in wait next time type in which version becase diamond pearl and platinum are different d/p veilstone city platinum hearthome.
There is no Pokemon Mansion, it was destroyed by the Volcanic Eruption in Cinnabar.
vulpix is not in Pokemon platinum version.
Yes creselia is is in Pokemon Platinum.
At the mansion,trophy garden to get there you have to go to hearthome city then go to the bottom left of the city and you will see 2 ways one to the left and one to the bottom so take the bottom one and keep going until you enter the mansion then enter the first room straight and walk around in the grass till a pikachu or pichu come out
You can't really catch Rayquaza through normal gameplay. However, you can migrate Rayquaza from Pokemon Ruby, Sapphire, or Emerald version to Pokemon Platinum version.In the tower near the place you find Spirtomb passed Hearthome City and below the town with the Daycare.