Do Nintendo events ever repeat themselves?

Answer 1

Yes they do, but it rarely happens in a single game. But since your talking about Pokemon its okay. Usually in another game they have the same Pokemon your looking for. I'll even give you a list of the upcoming events.

Mew for Heart Gold and Soul Silver.

Enigma Crystal for Heart Gold and Soul Silver. ( Lets you battle Latios or Latias depending on your version of the game.)

Movie Scizor for Heart Gold and Soul Silver.

Heatran for Pokemon Ranger Guardian Signs which is yet to come out in any other country but Japan.

Shaymin for Pokemon Ranger Guardian Signs.

Manaphy for Pokemon Ranger Guardian Signs.

(Go to Seribii.net for more info)

Hope I helped!