Random thought: the Sevii Islands is Nintendos way of giving us Orange Islands in game. Edit
The common wisdom Orange Islands has never been in an official Pokemon game. I reckon the Sevii islands is the closest Nintendo done to making the Orange islands. It's so similar, except for name. Hear me out.
She plays a VERY important part in the (short/tacked on) story of the Sevii islands. In the anime, she was on in the orange islands while in the game she was in the Sevii islands - they didn't explain the change at all.
In Pokemon 2000 (2nd movie), they mention Moltres is thought to have originated in "a remote part of the Orange Islands". Of course in FireRed/LeafGreen, it is obtainable from the peak of Mt. Ember (on Knot Island, the first of the Sevii Islands). Zapdos and Articuno are still available in the the same places.
Of course, there are many more islands in the Orange Archipelago than the Sevii Archipelago, it would be hard to navigate ingame otherwise. Also note that most cities (for example Viridian City) is much different in the game than in the anime. Put it down to artistic licence.
I think wanted the Orange islands in a game for completeness, Nintendo's addition of the Sevii Islands is the closest thing we'll ever get. All we needed is a renaming of the islands + Profressor Ivy + GS Ball + Celebi + Laprases + the character Tracy Sketch and we'd be done :D
10:20, September 28, 2010 (UTC)