While what Viola said is true, Pretendo also just launched a method on the Wii U side of things where modding your console is completely unnecessary, and I believe it functions similar to how Poke Classic Network does for the Gens 4 & 5 games, by using a custom DNS port. Hopefully something like that will be developed for the 3DS in the future!

ncG1vNJzZmiapaGvorPAq5uepl6jsrV706GpnpmUqHy0u4ytn6Kmm2LEprjLZp6erF2Weqetzaycq66Vp3qnu9Fmq6GdXWixtHnGmqSeq15ofXJ%2BlHFm