PokeMaster99999

Also, after using this, I can no longer get Shadow Togepi; Hordel just says "your party's full", even when I only have 5 or fewer Pokémon in said party.

As far as I know, there's no weird Missingno. in the last slot; I can't select it in the overworld party screen, the battle party screen, or within a PC; and when I battle Willie, the last Poké Ball up top is completely empty. So I don't get why Hordel keeps saying "your party's full". 

I wish there was a way to increase the number of Shadow Pokémon with this; in the Trainer Editor, the "Shadow -" entries don't save any changes. Shame, because I wanted a Shadow Machop and Shadow Vigoroth...heck, Shadow Latios.

I did find a file called "DeckData_DarkPokemon.bin" in the Decks folder, but I can't uncompress it with The Unarchiver. Odd.

...How exactly did Pokémon XG get 100 Shadow Pokémon? I'd hack that, but I don't really want the new moves or anything.