This is WRONG. Hannover was decomissioned and struck from the navy list in 1936 and Scharnhorst and Gneisenau were fast battleships too - they were faster than Bismarck and Tirpitz
''No right or wrong in history'' ? Yes of course there is. Hannover was decommissioned in 1931, which means it no longer belonged to the German navy after that date and therefore falls outside your own definition - it never belonged to the Kriegsmarine. And my perception of a fast battleship is one that is faster than a regular battleship. Scharnhorst class were one or two knots faster than Bismarck class, in fact in many places they are regarded as 'battlecruisers'. The 'pocket' battleships were only referred as such in the British press, the Germans called them 'armoured ships' and then heavy cruisers, either of which is correct. You might not like being wrong but you are.
2. It depends on your perception of (Fast) Battleship anyway, just like the Deutschland Class which you may call them as Pocket Battleships
3. There's no right or wrong in history