As stated in the previous post that you made, that's basically how you play the wifi mode. I'll call it a mix of ctf and defend your base.

If you're on the offence, you try to get as many tetra (triangle thingy) to your base without getting killed by the phantom guards or by timeout. you can collect powerup around the map. They're mark by circles. You can take your opponent color power up too.

If you're on the defense, you control the 3 phantom guards by click on them in the screen and plotting their waypoint route on the screen using the stylus. Your guards can pick up power up too.

I'm not sure if i'm making sense but i'm sure you'll understand if you try it out.

Maybe I'll translate the menus in case you don't understand

Once you enter the wifi menu

the top screen shows the stats of you
the bottom screen
???????- Battle with other DS
???? - Online
?????? - Download Play
????? - Instructions on playing the wifi mode
?????? - Change your nickname
??????? - Friend List
???????? - Rare Play List ( This is basically your achievements that will be given to you from your online matches)

After wifi mode selected,

??????? Playing with your friends
???????? - Playing with those from japan who have the same rank
????????? - Playing with those from around the world who have the same rank
??????? - Playing with anyone from japan regardless of rank
????????? - Playing with anyone from around the world regardless of rank