This command only works if the specified user is in a full clash team. Only then Zoe sends an analysis of the team. If this command is sent within a clashchannel, the region is not mandatory.
Zoe gives you information about 3 possible picks, a flexpick and probable bans against your team.
If you want to analyse an opposing team, you need a gamename and tag (Riot ID) of a player of the opposing team.
None - every user on a server can use this command (as long as not further restricted by permission)