How good of a player is your sister?
Has she made any accomplishments pokemon wise?
I'm sorry, but I just find it hard to believe that this deck could beat all four of those decks.
Just curious, you did play more than one game against each deck, right?
I know I'm being harsh, but when I first started playing, I had wildly inconsistent decks, but I won against the bad players in my league, so I thought my deck was good. One of the good players at the league tryed to help me fix my deck, and I wouldn't listen to what he was saying. Remove my 1-1-1 walrein, 1-1-1 Empoleon, 1-1-1 infernape, and 1-1-1 venesaur, and make my 1-1-1 torterra and 1-1-1 machamp lines thicker and focus the deck around them only? Ridiculous. He then sighed and challenged me to a few games. I lost every single one. I startedvtaking his advice, and started doing much better because I had a better, more consistent deck. Even if you don't believe it, you shold try to just focus on one or two lines.
EDIT: I got ninja'd :C