EDIT:
 
  PHP- Kodu:
  /* Plugin generated by AMXX-Studio */
#include <amxmodx>
#include <amxmisc>
#include <cstrike>
#define PLUGIN "New Plug-In"
#define VERSION "1.0"
#define AUTHOR "JDM"
public plugin_precache() {
    precache_model("models/player/guerilla/guerilla.mdl")
    precache_model("models/player/arctic/arctic.mdl")
    precache_model("models/player/ndguards/ndguards.mdl")
}
public plugin_init() {
    register_plugin(PLUGIN, VERSION, AUTHOR)
    
    register_event("ResetHUD", "SetModel", "b")
}
public SetModel(id) {
    if(cs_get_user_team(id) == CS_TEAM_T) {
        switch(random(2)) {
            case 0: {
                cs_set_user_model(id, "guerilla");
            }
            case 1: {
                cs_set_user_model(id, "arctic");
            }
        }
    } else if(cs_get_user_team(id) == CS_TEAM_CT) {
        switch(random(1)) {
            case 0: {
                cs_set_user_model(id, "ndguards");
            }
        }
    } else {
        cs_reset_user_model(id)
    }
}