Many games that hold events, typically have event currencies. Should Pokemon Go add some kind of event currency? It will make events a bit more meaning full and depending on what the items traded for are. It should definitely be helpful. Not to mention it would add a bit of gameplay and a little more story to the event Niantic decides to hold.
As an example of how something like this would work. We could look at the upcoming Christmas event. For each Ice type Pokemon captured, hatched, or evolved, we could be rewarded a single "snowflake". These "snowflakes" would then be traded in for in-game content, but not just any content. Very specific items such as "holiday" or winter-related items.
These items could range anywhere from an x amount of stardust for each medal, candies for ice related Pokemon, and even incenses. In most places that can play Pokemon Go, it really isn't safe to stay outside for any longer than an hour. With this idea, it could help players progress, without needing to worry too much about their temperatures.
For an easter event, we could find eggs hidden within the encounter screen. To collect them, you would just need to tap on them. These could be used again for stardust, but more egg related things. Possibly even 2, 5, 10km eggs. This idea would give players a little something more to look forward to and can even add more medals the game.