After making my Sandstorm.found out that no 6vs6?!
 

I realized that there is no 6vs6 level 100 on random matchup in pokemon white and black. That is ridiculous... how am I supposed to use my OU sandstorm team to its fullest or test it at all against trainers when I can only use 3 of my pokemon?

Smogon uses Pokemon Showdown!, a fully online Pokemon simulator, for its battles; you can create your team there (it's easy) and use that. Alternatively, head over to the WiFi Battle Finder for 6v6 level 100 battles with fellow Smogon members.

In the future, use the Simple Questions, Simple Answers thread for questions like this.

What he said