How many event items are there in Pokemon platinum?

Answer 1

There are four event items in Pokémon Platinum, the first item which was available for a limited time was the Secret Key which would have allowed you to enter into a secret room in Team Galactic's Eterna Headquarters, the second item is the Member's Card which would have allowed you to travel to an island in order to encounter and attempt to catch Darkrai, the third item is Oak's Letter which would have allowed you to encounter an in-game Shaymin so that you could attempt to catch it and the fourth and last one was the Azure Flute which was never available, the Azure Flute would have allowed you the chance if it was available to encounter Arceus so that you could try to catch it.