This has probably been thought of before, but I think it'd be nice to have a pet that isn't just a pretty decoration next to you. I love collecting pets but it always gets me that I'm spending a good amount of gold for something that's just dead weight next to you.
I would love to see a new line of pets that could actually help you in battle! The only problem I can see is what happens if it's defeated. With a minion, it just goes back in the deck. It'd be great if the pet were in destructable, but I suppose to be fair to the enemy (like we need to be when they're 3000 points and up!) they could probably only cast minor spells.
And, because I'm feeling lazy and don't want to start another whole thread, I think it'd be nice to be able to summon more then one minion. Especially since sometimes the minion you summon isn't too bright haha Mine seem to love getting themselves killed and then the summon cards are like "hey, let's not show up again, that'll be funny!" I think more minions would be very helpful - but maybe it could be made into a certain card so that you can't have multiple minions until a certain level.