For all the people having problems.
First of all, make sure one of you haves a "loaded" team (the one who will be challenged). For Example, when you get challenged, your team appears in the window without need of searching for it.
Once you got that done, the guy who will send the challenge, dont click "random battle" until he has loaded a team (this time with the "search for team" thing). Once you loaded a team, click random battle, and the team should disappear as always. Send a challenge to the guy whos team is in auto-load and wait for him to click accept.
This should work, thats how TAY and me did ours after like 15 tries.