Hello!

As far as I know, 3v3 Arena isn't the same anymore as it was first introduced. During the first couple of 3v3 months, you can enter 3v3 alone and find teammates by searching throughout the region but now, it requires you to have a team from your own server before you can enter a battle, searching also only searches players within your server whose currently in search mode also.

If I'm wrong, please correct me. I haven't tried entering 3v3 Arena alone and can't try it now since it is not open yet (3AM right now). Thank you.