The main reason for why you can't see who's in the arena is that so you can't duel with a specific Iczer.
If you could see the battle list and user list, you might be able to time it just right to duel with your friend (or could be yourself with another account), who might let you win/lose.
I don't want to suspect that anyone will do such a thing, but we have to be very careful.
It's just another precaution to prevent people from cheating the system.
reydien wrote:As far as I can tell, you can't friend someone unless you duel them...
You can also add your friends to your friend list in Chat on My Iczer page or Game home page.
You still have to send a PM to whoever you want to be friend with, and ask them to go to Chat at a specific time, make a room and ask them to enter your chat room.
Or just like Grain suggested, go to training arena and make a room for your friend, and add them that way.