Okay, I think I've worked out a way to use it. First, don't try to catch anything while the cheat is active, just go directly to your stat shop menu and it should show you able to purchase anything, after buying something you'll unlock a ton of stuff that you have to wait through.
Even if you get stuck at the armory like I did, turn the cheat on again and use the armory or stat menu to boost your backpack size by a lot, then catch enough ghosts in the armory area to reach level 3.
Hope this helps anyone confused like I was.