Pygmy Puff

I'm new here...

So Pygmy Puffs. They’re invented by Fred and George (I think just George invented them) If I recall correctly. Anyway remember when they banned all things from Weasleys’ Wizard Wheezes from Hogwarts? How did they allow Ginny to have Arnold? It really confuses me, I mean did she sneak him in? Did they make an exception? Did no one notice? Or was that rule in place in Professor Umbridge’s rein? I don’t think so because I think professor Filch put that rule into action. Someone please help.

Who agrees with this