I had a bit of a think for AL invite lobbies, and what about this method to make the player reliable and get a verification of skills?
AL User invites normal user.
Invited user stays on a stage called "AL INVITE" for 2/3 weeks
User plays AL INVITE ONLY lobbies.
After the 3 weeks time has passed, the AI or normal players rate the invited user's skill.
If he has a positive vote, he will get the possibility to enter normal AL lobbies, if not, the user needs another invite to try another time and wait another 3 weeks then do the real tryout of 3 weeks.
Also, users can invite to these lobbies only users that are in the same region, cause VPNs and alts.
