I made a community for any pokebay MK7 3DS players, so you can just add the community instead of having to add everyone's friend code. Post here if you want to race and that you will be waiting in the online community at whatever time.
In order to access the community, go to online multiplayer in your MK game, and once you are connected to the internet, click on the third option, "communities". Then, use the "search by code" to find the pokebay community! It has the blue shell as its avatar.
The community code is
55-3535-5909-7951
Once people start racing, the community itself has its rankings depending on points you earn from races. Have fun! :'D