To form North Germany you need the following:

• Admin Tech 15, otherwise 800 splendor
  
• Was never an end game tag
  
• Culture: Hannoverian, Pommeranian, Lower Saxon, Hessian, Saxon, Prussian
  
• Own: Berlin, Hessen, Brunswick
  
• Own 4: Frankfurt, Oldenburg, Dresden, Köln, Königsberg, Urach, Schleswig, Ratibor
  
• Or:
  
  • Highest development in North Germany
    
  • Biggest army in North Germany

To found Bundesrat you need all of the above as well as the following:

• Diplo Tech 15, otherwise 400 splendor
  
• Or:
  
  • Own 6: Frankfurt, Oldenburg, Dresden, Köln, Königsberg, Urach, Schleswig, Ratibor, Hamburg, Rostock
    
  • Diplo Tech 20, 75 prestige & 3 subjects

With Bundesrat North German countries join you over time and you inherit them.