Are all PVP battles with RANDOM teams?

I want to know how to fight against my friends, and also choose who I will be entering into PVP matches with. How can I do this?? So far, the only thing I see is random team based PVP battles in the Arena in Ascalon. Surely there's a way to fight with or against your friends??

The Tombs allows you to pick your teammates, and there may be other arenas that do this too.