kman,

Here is a snippet that might help get you started. The male_mutants (guard.mdl) fade in just after the level loads. Pressing the 2 key (change to your panel button) fades the male_mutants out and fades the female_mutants (cbabe.mdl) in. The 1 key reverses this process. I used the create and remove method instead of the visible and invisible method to save framerate. Maybe you can use this template to add your cyborgs and other races. This has been tested in a empty level with the exception of a position (default camera).

/////////////////////////////////////////////////////////////////
// The MAIN function is called at game start
function main()
{
load_level(<KmanProj.WMB> );
load_status(); // restore global skills
// client_move(); // for a possible multiplayer game
// call further functions here...
WAIT(5);
spawn_male_mutants();// spawn male mutants upon loading
}

SYNONYM syn_male_fire_mutant {type entity;}
SYNONYM syn_male_water_mutant {type entity;}
SYNONYM syn_male_3_mutant {type entity;}
SYNONYM syn_male_4_mutant {type entity;}
SYNONYM syn_male_5_mutant {type entity;}
SYNONYM syn_male_6_mutant {type entity;}
SYNONYM syn_male_7_mutant {type entity;}

SYNONYM syn_female_fire_mutant {type entity;}
SYNONYM syn_female_water_mutant {type entity;}
SYNONYM syn_female_3_mutant {type entity;}
SYNONYM syn_female_4_mutant {type entity;}
SYNONYM syn_female_5_mutant {type entity;}
SYNONYM syn_female_6_mutant {type entity;}
SYNONYM syn_female_7_mutant {type entity;}

// toggle models
FUNCTION m_m_from_f_m () {//male_mutants_from_female_mutants
remove_female_mutants ();
WAITT(10);
spawn_male_mutants ();
}

FUNCTION f_m_from_m_m () {//female_mutants_from_male_mutants
remove_male_mutants ();
WAITT(10);
spawn_female_mutants ();
}

/// MALE MUTANTS
/// functions to spawn the male mutant models
FUNCTION spawn_male_mutants () {
spawn_male_fire_mutant ();
spawn_male_water_mutant ();
spawn_male_3_mutant ();
spawn_male_4_mutant ();
spawn_male_5_mutant ();
spawn_male_6_mutant ();
spawn_male_7_mutant ();
}

FUNCTION spawn_male_fire_mutant{
temp.x=35;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_fire_mutant);

}

function spawn_male_water_mutant{
temp.x=135;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
create(<guard.mdl>,temp,male_water_mutant);
}

FUNCTION spawn_male_3_mutant{
temp.x=235;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_3_mutant);

}

FUNCTION spawn_male_4_mutant{
temp.x=335;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_4_mutant);

}

FUNCTION spawn_male_5_mutant{
temp.x=435;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_5_mutant);

}

FUNCTION spawn_male_6_mutant{
temp.x=535;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_6_mutant);

}

FUNCTION spawn_male_7_mutant{
temp.x=635;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<guard.mdl>,temp,male_7_mutant);

}

/// functions to set synonyms and fade in
FUNCTION male_fire_mutant{
syn_male_fire_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_water_mutant{
syn_male_water_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_3_mutant{
syn_male_3_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_4_mutant{
syn_male_4_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_5_mutant{
syn_male_5_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_6_mutant{
syn_male_6_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION male_7_mutant{
syn_male_7_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}


/// functions to remove the male mutant models
FUNCTION remove_male_mutants () {
remove_male_fire_mutant ();
remove_male_water_mutant ();
remove_male_3_mutant ();
remove_male_4_mutant ();
remove_male_5_mutant ();
remove_male_6_mutant ();
remove_male_7_mutant ();
}

FUNCTION remove_male_fire_mutant () {
syn_male_fire_mutant.TRANSPARENT = ON;
syn_male_fire_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_fire_mutant.ALPHA -= 5*TIME;
IF(syn_male_fire_mutant.ALPHA <=0)
{
REMOVE syn_male_fire_mutant;
//syn_male_fire_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_water_mutant () {
syn_male_water_mutant.TRANSPARENT = ON;
syn_male_water_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_water_mutant.ALPHA -= 5*TIME;
IF(syn_male_water_mutant.ALPHA <=0)
{
REMOVE syn_male_water_mutant;
//syn_male_water_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_3_mutant () {
syn_male_3_mutant.TRANSPARENT = ON;
syn_male_3_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_3_mutant.ALPHA -= 5*TIME;
IF(syn_male_3_mutant.ALPHA <=0)
{
REMOVE syn_male_3_mutant;
//syn_male_3_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_4_mutant () {
syn_male_4_mutant.TRANSPARENT = ON;
syn_male_4_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_4_mutant.ALPHA -= 5*TIME;
IF(syn_male_4_mutant.ALPHA <=0)
{
REMOVE syn_male_4_mutant;
//syn_male_4_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_5_mutant () {
syn_male_5_mutant.TRANSPARENT = ON;
syn_male_5_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_5_mutant.ALPHA -= 5*TIME;
IF(syn_male_5_mutant.ALPHA <=0)
{
REMOVE syn_male_5_mutant;
//syn_male_5_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_6_mutant () {
syn_male_6_mutant.TRANSPARENT = ON;
syn_male_6_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_6_mutant.ALPHA -= 5*TIME;
IF(syn_male_6_mutant.ALPHA <=0)
{
REMOVE syn_male_6_mutant;
//syn_male_6_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_male_7_mutant () {
syn_male_7_mutant.TRANSPARENT = ON;
syn_male_7_mutant.ALPHA = 100;
WHILE(1)
{
syn_male_7_mutant.ALPHA -= 5*TIME;
IF(syn_male_7_mutant.ALPHA <=0)
{
REMOVE syn_male_7_mutant;
//syn_male_7_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

/// FEMALE MUTANTS
/// functions to spawn the female mutant models
FUNCTION spawn_female_mutants () {
spawn_female_fire_mutant ();
spawn_female_water_mutant ();
spawn_female_3_mutant ();
spawn_female_4_mutant ();
spawn_female_5_mutant ();
spawn_female_6_mutant ();
spawn_female_7_mutant ();
}

FUNCTION spawn_female_fire_mutant{
temp.x=35;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_fire_mutant);

}

function spawn_female_water_mutant{
temp.x=135;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
create(<cbabe.mdl>,temp,female_water_mutant);
}

FUNCTION spawn_female_3_mutant{
temp.x=235;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_3_mutant);

}

FUNCTION spawn_female_4_mutant{
temp.x=335;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_4_mutant);

}

FUNCTION spawn_female_5_mutant{
temp.x=435;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_5_mutant);

}

FUNCTION spawn_female_6_mutant{
temp.x=535;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_6_mutant);

}

FUNCTION spawn_female_7_mutant{
temp.x=635;
temp.y=355;
temp.z=275;
vec_for_screen(temp,camera);
CREATE(<cbabe.mdl>,temp,female_7_mutant);

}

/// functions to set synonyms and fade in
FUNCTION female_fire_mutant{
syn_female_fire_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_water_mutant{
syn_female_water_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_3_mutant{
syn_female_3_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_4_mutant{
syn_female_4_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_5_mutant{
syn_female_5_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_6_mutant{
syn_female_6_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}

FUNCTION female_7_mutant{
syn_female_7_mutant = ME;
MY.TRANSPARENT = ON;
MY.ALPHA = 0;
WHILE(1)
{
MY.ALPHA += 5*TIME;
IF(MY.ALPHA >=100)
{
MY.TRANSPARENT = OFF;
RETURN;
}
WAIT(1);
}
}


/// functions to remove the female mutant models
FUNCTION remove_female_mutants () {
remove_female_fire_mutant ();
remove_female_water_mutant ();
remove_female_3_mutant ();
remove_female_4_mutant ();
remove_female_5_mutant ();
remove_female_6_mutant ();
remove_female_7_mutant ();
}

FUNCTION remove_female_fire_mutant () {
syn_female_fire_mutant.TRANSPARENT = ON;
syn_female_fire_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_fire_mutant.ALPHA -= 5*TIME;
IF(syn_female_fire_mutant.ALPHA <=0)
{
REMOVE syn_female_fire_mutant;
//syn_female_fire_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_water_mutant () {
syn_female_water_mutant.TRANSPARENT = ON;
syn_female_water_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_water_mutant.ALPHA -= 5*TIME;
IF(syn_female_water_mutant.ALPHA <=0)
{
REMOVE syn_female_water_mutant;
//syn_female_water_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_3_mutant () {
syn_female_3_mutant.TRANSPARENT = ON;
syn_female_3_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_3_mutant.ALPHA -= 5*TIME;
IF(syn_female_3_mutant.ALPHA <=0)
{
REMOVE syn_female_3_mutant;
//syn_female_3_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_4_mutant () {
syn_female_4_mutant.TRANSPARENT = ON;
syn_female_4_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_4_mutant.ALPHA -= 5*TIME;
IF(syn_female_4_mutant.ALPHA <=0)
{
REMOVE syn_female_4_mutant;
//syn_female_4_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_5_mutant () {
syn_female_5_mutant.TRANSPARENT = ON;
syn_female_5_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_5_mutant.ALPHA -= 5*TIME;
IF(syn_female_5_mutant.ALPHA <=0)
{
REMOVE syn_female_5_mutant;
//syn_female_5_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_6_mutant () {
syn_female_6_mutant.TRANSPARENT = ON;
syn_female_6_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_6_mutant.ALPHA -= 5*TIME;
IF(syn_female_6_mutant.ALPHA <=0)
{
REMOVE syn_female_6_mutant;
//syn_female_6_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

FUNCTION remove_female_7_mutant () {
syn_female_7_mutant.TRANSPARENT = ON;
syn_female_7_mutant.ALPHA = 100;
WHILE(1)
{
syn_female_7_mutant.ALPHA -= 5*TIME;
IF(syn_female_7_mutant.ALPHA <=0)
{
REMOVE syn_female_7_mutant;
//syn_female_7_mutant.INVISIBLE = ON;
RETURN;
}
WAIT(1);
}
}

/////////////////////////////////////////////////////
ON_1 m_m_from_f_m;
ON_2 f_m_from_m_m;

///////////////////////////////////
EDIT:
Oops, I forgot to put this in the code format. Actually it is easier to copy and paste this way.

Good luck