Pokémon Mystery Dungeon: Blue Rescue Team and Red Rescue Team/Silent Chasm

Once you have beat Sinister Woods walk into Pokémon Square. You'll see a Jumpluff trying to make a Shirtry and two Nuzleaf rescue Jumpluff's friend. Before you enter Silent Chasm Jumpluff will tell you to go to 10f, then it will tell you that there is a monster, which is Zapdos.

The Dungeon
There is no chance of finding a Monster House, a shop, or a buried item in this dungeon.

Enemies
You do not have to battle Zapdos just yet. Zapdos will take Shiftry away and you'll rescue Jumpluff.