//ANTI TEAMKILL
public OnGameModeInit()
{
  SetTimer("UpdateTeams", 1000, 1);
  return 1;
}

forward UpdateTeams();
public  UpdateTeams()
{
  for(new i = 0; i<GetMaxPlayers(); i++)
  {
   if(gTeam[i] == 1) { SetPlayerTeam(playerid, 1); }
   else if(gTeam[i] == 2) { SetPlayerTeam(playerid, 2); }
  }
}

	for(new i = 0; i < MAX_PLAYERS; i++)
	{
		if(IsPlayerConnected(i))
		{
			if (player admin / rank ; whatever you use to get your player admin status)
			{
			  new playerip[20];
				new playername[MAX_PLAYER_NAME];
				new string[256];
				GetPlayerName(playerid, playername, sizeof(playername));
				GetPlayerIp(playerid, playerip, sizeof(playerip));
				SendClientMessage(i, your desired color, "%s has left the game. IP: %s.", playername, playerip);
			}
		}
		return 1;
	}

// top of your gamemode
forward SettingPlayerTeam();
//OnPlayerConnect
SetTimerEx("SettingPlayerTeam",10,1,"d",playerid);
//Bottom of your script
public SettingPlayerTeam()
{
  for(new playerid; playerid < 200; playerid++)
    SetPlayerTeam(playerid, gTeam[playerid]);
  return 1;
}



i found this from seif