I TOTALLY feel you on this.
Here's what I did when this was an issue for me.
We played THEME DECKS from EACH set. I would read the little rule book's "WHAT'S CHANGED" section and we'd play games with the new theme decks with the new rule changes during that week.
I would preface the game with an explanation of what's changed like
"Ok sweetheart. This is what we need to remember now. _____ are no longer _______" So, do everything that we did last week except _____ can no longer _____ "
If we switched out to earlier theme decks, we'd, still, play by the newest rules that we have learned.
We did this from BASE SET 2 .. .all the way up to Diamond and Pearl.
As a result, I ended up knowing the rules better than most because I was reading them rather than depending upon word of mouth.
Now.. as far as STRATEGY GOES... the pokepowers/pokebodies have become more important than ever before. Some ENTIRE DECK STRATEGIES evolve around a combo of pokepowers.
DON'T WORRY ABOUT ALL OF THAT YET...
Just get two theme decks per set... each week... and play it up.
Your daughter will have SO MUCH FUN doing this with you and you will be skin-tight on rules, procdures, game mechanics.