Taken from Nintendo's Network Maintenance Information/Operational Status page:
FROM THURSDAY, MARCH 13, 2014 1:00 PM-THURSDAY, MARCH 13, 2014 5:00 PM PACIFIC TIME
AFFECTED SERVICES:
Wii U
- Nintendo eShop
Nintendo 3DS
- Nintendo eShop
Wii
- Wii Shopping Channel
Nintendo DS
- Nintendo DSi Shop
FROM MONDAY, MARCH 10, 2014 5:00 PM-TUESDAY, MARCH 11, 2014 7:00 AM PACIFIC TIME
AFFECTED SERVICES:
Nintendo 3DS
- Online Play, Rankings, etc. for Pokémon™ X, Pokémon™ Y
FROM THURSDAY, MARCH 13, 2014 1:00 PM-THURSDAY, MARCH 13, 2014 5:00 PM PACIFIC TIME
AFFECTED SERVICES:
Wii U
- Nintendo eShop
Nintendo 3DS
- Nintendo eShop
Wii
- Wii Shopping Channel
Nintendo DS
- Nintendo DSi Shop
FROM MONDAY, MARCH 10, 2014 5:00 PM-TUESDAY, MARCH 11, 2014 7:00 AM PACIFIC TIME
AFFECTED SERVICES:
Nintendo 3DS
- Online Play, Rankings, etc. for Pokémon™ X, Pokémon™ Y