[Hiddos]

pawn Код:

new GMs[][32] = {
  {"lvdm"},
  {"grandlarc"},
  {"rivershell"}
};

stock LoadRandomGm()
{
  new string[43];
  format(string, sizeof string, "changemode %s", GMs[random(sizeof GMs)]);
  SendRconCommand(string);
}

Might get some errors at the format(string, bla) crap, but something like that should do the trick.

Place all your GMs in a variable and random them.