LGPE Legendary Bird Spawn Calculator.cs

bool lure_active = true;
string output = "";

void Main()
{
    // Initial state
    ulong s0 = 0x0123456789ABCDEF;
    ulong s1 = 0x0123456789ABCDEF;

    // Set this for how far you want to search.
    int maxAdvance = 1000;

    var rng = new Xoroshiro128Plus(s0, s1);
    for (int advances = 0; advances < maxAdvance; advances++)
    {
        var (_s0, _s1) = rng.GetState();
        output = $"{advances:00000} | {_s0:x16} | {_s1:x16} |";
        GetStateLGPEBird(advances, rng, 1);
        rng.Next();
    }
}

// You can define other methods, fields, classes and namespaces here
private void GetStateLGPEBird(int advance, Xoroshiro128Plus rng, int try_no)
{
    if (try_no is not (1 or 2))
        return;

    var check = rng.Next();
    var rand = (uint)(check % 10000);

    ulong bird = 0;
    
    if (rand <= 4)
    {
        output += $" Bird generated on try #{try_no}! | {rand} | ";
        bird = (uint)(rng.Next() % 3);

        switch (bird)
        {
            case 0:
                output += "Moltres";
                break;
            case 1:
                output += "Zapdos";
                break;
            case 2:
                output += "Articuno";
                break;                
        }
    }
    else if (lure_active && try_no != 2) // Active lure gives a second try.
    {
        GetStateLGPEBird(advance, rng, 2);
        return;
    }

    // Add your filters here.
    if (rand > 4)
        return;

    if (bird != 1) // Zapdos only.
        return;

    Console.WriteLine(output);
}

Setup is:

1. Download/install LINQPad (latest version is fine).
2. Download dev build PKHeX from https://projectpokemon.org/home/files/file/2445-pkhex-development-build/
3. Press F4 in LINQPad and add PKHeX.Core.dll to first tab, and PKHeX.Core to second tab,
4. Change the language at the top to C# program, then copy/paste the script in verbatim.
5. Edit your params at the top and any filters.
6. Click run.

Recommended LINQPad settings so output is monospaced:

1. Edit > Preferences > Results
2. Click "Launch Editor" under Style Sheet for text (HTML) results.
3. Paste this snippet and "Apply Changes".

   body
   {
   	margin: 0.3em 0.3em 0.4em 0.4em;
   	font-family: Consolas;
   }