Well some of us are in Oshi already so if they steal something from there it would be just stupid. if they take them from ormo... well you can tell, also xioi got into ormo so maybe he knows.
Again this would be solved by testing them ingame. And by their join date as well. If he joined in sep 2015 there is no way he spars/parkours like xioi for instance.

A deep research on the applicant would solve almost any problem.