Like the previous Dungeon games and the main games, Pokémon Mystery Dungeon: Adventure Squad has a variety of special events obtained over the Nintendo WiFi Connection. However, as they are on the Wii, there are two different methods to obtain WiFi Events, and the events vary between them.

WiiConnect24

The WiiConnect24 method requires you to only have the WiiConnect24 feature turned on on the Wii. With this on, during the days the event is active, the game will recognise this and the event will become active. The events obtained via WiiConnect24 are as follows:

Mew
Release Dates:

Japan: August 7th 2009 to August 16th 2009
America: ???
Europe: ???

Gift:
Pokémon: Mew


Dungeons:
Chocolate Mountain
Chocolate Island
Chocolate Field

Details:
When the event is active, you will be notified of Mew being in the dungeons where Farfetch'd lost a chocolate bar. In this dungeon (depending on the game), you will find Mew hidden away on 15F. It will sometimes be transformed so be vigilant. Unfortunately, it is not guaranteed to join your squad so you will have to keep trying to get it.


Darkrai
Release Dates:

Japan: August 20th 2009 to September 12th 2009
America: ???
Europe: ???

Gift:
Pokémon: Darkrai


Dungeons:
Path to Treasure Valley
Path to Treasure Mountain
Path to Treasure Island

Details:
When the event is active, you will be notified of Darkrai being in the dungeons where Farfetch'd lost a cookie. In this dungeon (depending on the game), you will find Darkrai hidden away on 15F. Unfortunately, it is not guaranteed to join your squad so you will have to keep trying to get it.


Jirachi
Release Dates:

Japan: September 15th 2009 to October 12th 2009
America: ???
Europe: ???

Gift:
Pokémon: Jirachi


Dungeons:
???

Details:
When the event is active, you will be notified of Jirachi being in the one of the dungeons (depending on the game), you will find Jirachi hidden away on 20F. Unfortunately, it is not guaranteed to join your squad so you will have to keep trying to get it.


Palkia
Release Dates:

Japan: October 15th 2009 to November 15th 2009
America: ???
Europe: ???

Gift:
Pokémon: Palkia


Dungeons:
???

Details:
When the event is active, you will be notified of Palkia being in the one of the dungeons (depending on the game), you will find Palkia hidden away on 15F. Unfortunately, it is not guaranteed to join your squad so you will have to keep trying to get it.


WonderMail W

The WonderMail W feature is found within the menu before you load up your game. These WonderMail W missions will give you special missions that you cannot normally find within game. However, unlike the ones in Dungeon Sky and Dungeon Time & Darkness, these WonderMail missions are not obtainable via password. The missions here are as follows

Arceus
Release Dates:

Japan: August 20th 2009 to ???
America: ???
Europe: ???

Difficulty: 5 (2000)
Reward:
Pokémon: Arceus (Fire) - Blazing
Arceus (Water) - Stormy
Arceus (Electric) - Light

Dungeons:
Final Mountain
Final Island
Final Cave

Details:
With this mission, you have to go to 29F of the final dungeon in the specific game you are playing. When you reach 29F, you will discover Arceus and he will challenge you. Defeat Arceus and the mission is complete and Arceus will join your Adventure Squad.