War against Brandenburg was tricky, since Austria was guaranting Brandenburg. So I made the war a little after Austria declared in Ottomans with help of Poland (AI player in the moment) and haters of Brandenburg.
As far I remember, it was (Pomerania, Saxony, Mecklenburg, Brunswick, Poland) against (Austria, Bohemia, Brandenburg, Ulm, Ansbach)
Austria was fighting Ottomans, and didn't do anything in early war, so Poland that was rival of Bohemia, did a fine job fighting Bohemia, while others allies fight against Brandenburg, Ulm and Ansbach.
After Austria finished peace with Ottomans, I tried to get a peace with Austria, but got denied. So I made a simple peace with Bohemia to get less people in the way. The highlight in fighting was this battle, it was 68.2k against 38.2k soldiers fighting and Poland side losing it. But I arrived with my stacked 24k soldiers (attached with many allies) to help the fight!
After Poland and me getting some territories, I got Austria paying war reparations to me in peace terms.
I did peace with Braundeburg, but I was already happy with war outcome and didn't checked the agressive expansion, so I got a large coalition against me. RIP me next session.