[Calisthenics]

AdminLevel1 should be an integer.

When you have repeated code, make it a function.
You can use ternary operator for "Yes"/"No".
Based on its name, when "Hide" is 1 shouldn't have been admin level 0? If not, change it in the code.

PHP Code:

CMD:stats(playerid, params[]) 
{
    new player1;
    if (sscanf(params, "i", player1)) player1 = playerid;
    ShowStatsForPlayer(playerid, player1);
    return 1;
}
ShowStatsForPlayer(viewer, target)
{
    new string[500], h, m, s;
    TotalGameTime(target, h, m, s);
    format(string, sizeof string,
        "{ff4d4d}Stats of %s\n\n{FFFFFF}Registered: %s\nLoggedIn: %s\nAdmin Level: %d\nScore: %d\nTime: %d hrs %d mins %d secs\nPing: %d\nCountry: %s\
        \n\n{33AA33}Cash: $%d\nBank: $%d\n\n{FFFFFF}Skin: %d\nWanted level: %d\n\n{FFFF00}Kills and Deaths\n{FFFFFF}Kills: %d\nDeaths: %d\nRatio: %f", 
        pName(target),
        PlayerInfo[target][Registered] == 1 ? ("Yes") : ("No"),
        PlayerInfo[target][LoggedIn] == 1 ? ("Yes") : ("No"),
        PlayerInfo[target][Hide] == 1 ? 0 : PlayerInfo[target][Level],
        GetPlayerScore(target),
        h, m, s,
        GetPlayerPing(target),
        GetPlayerCountryName(target),
        GetPlayerMoney(target),
        PlayerInfo[target][Bank],
        GetPlayerSkin(target),
        GetPlayerWantedLevel(target),
        PlayerInfo[target][Kills],
        PlayerInfo[target][Deaths],
        PlayerInfo[target][Deaths] == 0 ? (Float: PlayerInfo[target][Kills] / Float: 1) : (Float: PlayerInfo[target][Kills] / Float: PlayerInfo[target][Deaths]));
    return ShowPlayerDialog(playerid, 0, DIALOG_STYLE_MSGBOX, "Stats", string, "Ok", "");
}