It's really fun, you should try it with us :D
Go to the GTS and put a crap pokemon up. You can see more pokemon being offered in the GTS if you do so.
Make sure you have your friends registered in your pal pad. Using the chatbox on tornworld is also good for quick communication.
Now start searching A-Z, and clicking on all the offers that pop up, until you find a shiny.
You then put something up like a.. Shiny Darkrai for whatever they want for said shiny.
Then you trade for it.
Example: Haruka traded a Shiny Darkrai for a lvl.100 Meditite
Haruka sends meditite over to me.
I trade the Meditite for a Shiny Tangela.
The reason why it worked like that was because only I could see the shiny tangela. She couldn't, for some odd reason. and sometimes there will be offers like that, that you can't see. That's why it's best to work in groups when you go Shiny searching.
So, I guess this counts as a wifi activity.. at least I think.
((Will update later when I get home))