[EFFx]

It'll work only if the plugin is named as 'teamswitcher', otherwise the code you provided will do nothing, check this:

PHP Code:

#include <amxmodx>
#include <amxmisc>
#include <cstrike>

#define PLUGIN "Unknown yet"
#define VERSION "1.0"
#define AUTHOR "EFFEX"

new g_iRoundsWon[CsTeams], CsTeams:g_csTeamWon
new bool:g_bPluginOn, bool:g_bTeamsSwitched, pCvarMinRoundsToSwitch

public plugin_init() 
{
    register_plugin(PLUGIN, VERSION, AUTHOR)
    
    pCvarMinRoundsToSwitch = register_cvar("minrounds_to_switch", "10")
    register_concmd("amx_switch", "cmdStopSwitch", ADMIN_KICK, "<1|0> - turn the switch plugin on/off")
    
    register_event("TextMsg", "event_roundRestarted","a", "2&#Game_C", "2&#Game_w")
    register_event("SendAudio", "event_TerroristsWin","a", "2&%!MRAD_terwin") 
    register_event("SendAudio", "event_CTerroristsWin","a", "2&%!MRAD_ctwin")
    
    g_bPluginOn = true
}

public cmdStopSwitch(id, iLevel, iCid)
{
    if(!cmd_access(id, iLevel, iCid, 2))
        return PLUGIN_HANDLED
        
    new szMode[3]
    read_argv(1, szMode, charsmax(szMode))
    
    g_bPluginOn = bool:str_to_num(szMode)
    console_print(id, "[AMXX]: The switch teams is now %sativated!", g_bPluginOn ? "" : "de")
    return PLUGIN_HANDLED
}

public event_roundRestarted()
{
    if(!g_bTeamsSwitched)
    {
        g_iRoundsWon[CS_TEAM_T] = g_iRoundsWon[CS_TEAM_CT] = 0
    }
    else g_bTeamsSwitched = false

public event_TerroristsWin()
{
    if(!g_bPluginOn)
        return
        
    if(++g_iRoundsWon[CS_TEAM_T] >= get_pcvar_num(pCvarMinRoundsToSwitch))
    {
        g_csTeamWon = CS_TEAM_T
        set_task(0.1, "printColoredHudMessage", .flags = "a", .repeat = 30)
        
        set_task(3.5, "switchTeams")
    }
}

public event_CTerroristsWin()
{
    if(!g_bPluginOn)
        return
    
    if(++g_iRoundsWon[CS_TEAM_CT] >= get_pcvar_num(pCvarMinRoundsToSwitch))
    {
        g_csTeamWon = CS_TEAM_CT
        set_task(0.1, "printColoredHudMessage", .flags = "a", .repeat = 30)
        
        set_task(3.5, "switchTeams")
    }
}

public printColoredHudMessage()
{
    static bool:bTemp
    
    new iRGB[3], bool:bTerrorWon = bool:(g_csTeamWon == CS_TEAM_T)
    switch(bTemp)
    {
        case true:
        {
            if(bTerrorWon)
            {
                iRGB = {255, 0, 0}
            }
            else iRGB = {0, 100, 255}
            
            bTemp = false
        }
        case false:
        {
            iRGB = {255, 255, 255}
            bTemp = true
        }
    }
    set_hudmessage(iRGB[0], iRGB[1], iRGB[2], -1.0, 0.3, 0, 1.0, 0.1)
    show_hudmessage(0, "The %sTerrorist team has won %d rounds!^nSwitching teams...", bTerrorWon ? "" : "Counter-", get_pcvar_num(pCvarMinRoundsToSwitch))
}

public switchTeams()
{
    new iPlayers[32], iNum
    get_players(iPlayers, iNum)
    for(new i, id;i < iNum; i++) 
    {
        if(1 <= get_user_team((id = iPlayers[i])) <= 2)
        {
            cs_set_user_team(id , cs_get_user_team(id) == CS_TEAM_T ? CS_TEAM_CT : CS_TEAM_T)
        }
    }
    g_bTeamsSwitched = true

    new iTemp = g_iRoundsWon[CS_TEAM_T]
    g_iRoundsWon[CS_TEAM_T] = g_iRoundsWon[CS_TEAM_CT]
    g_iRoundsWon[CS_TEAM_CT] = iTemp
    
    client_print(0, print_center, "Teams successfully swiched!")
    server_cmd("sv_restart 1")
}