I heard Nintendo Network is something to do with the Wii U connected to the internet, and I don't have a Wii U and if I did, I couldn't connect to the internet. So can you get it another way?
If your 3DS can connect to Nintendo Wifi then you should be fine to download the Torchic Event. If you cant connect however I'm sorry to tell you that you will not be able to receive the Torchic Event,