Here's a twofer:
First off, the Papal States in Northern Germany is huge. I was playing Naples in this game and booted them off the boot. They formed a huge country in north Germany until Austria cut them in half. Now, the Papal State is my ally and so when they called Austria and I to join them in an enormous war against nearly all the German Minors I admit I helped. I sent my army north to kill the tiny armies seiging Papal provinces and the Pope himself conquered as much as he could from them. So not 100% AI driven, but probably a good 75%. I'm just the Pope's guardian Angel.
2nd goodie. Take note of Brabant's Personal Union. (Austria is still huge, by the way). But that'll be the end of the Habsburgs, methinks.