On wifi, in Mario Tennis Open, there is a region lock. This means that you will only face players from your region.
EXAMPLE: If you are from the U.S. you will only face players from North and South America.
Now many people don't worry at all about this. The one major disadvantage this brings is that you can not, repeat CAN NOT, even play with FRIENDS from your ROSTER that don't share the same region as you!
This is absurd!
Even the 2005 game, Mario Kart DS had WORLD WIDE matches.
Nintendo CAN do better.
There is a way to help.
Call, 1-800-255-3700, Nintendo of America and complain about the MTO region lock so they will get it fixed! The more people that call, the more likely it will get fixed!
I, for one, will call every day until this is fixed or I get a complete return of my money.