[Robe]

As for Aircraft:
Hitler ordered Göring to produce aircraft for the carrier and under this pressure, the air marshall offered redesigned versions of the Junkers Ju 87B and the Messerschmitt Bf 109E-3, which were at that time being phased out of the Luftwaffe first-line squadrons. Raeder was unhappy, but he had to accept them or none at all (including Göring's insistence that the flying personnel would remain under Luftwaffe command). All this forced another delay in the construction of the carrier: the flight deck installations had to be changed.

From here :

http://en.wikipedia.org/wiki/German_aircraft_carrier_Graf_Zeppelin

[Tallguy]

The Bf-109's landing gear arrangement was barely adequate as it was. It's not clear how it could have been beefed up given that it had to retract outward into a fairly thin wing. Many Bf-109's suffered collapsed landing gears -- especially when operating from rough airfield in the East.

A better choice would have been the FW-190A. It had a wide-track landing gear that folded inward. Plus, it had a radial engine for ease of maintenance -- an important consideration for carriers. Folding wingtips, similar to the Zero could have been added.

Much is made of German aircraft designs making it to Japan. I guess German pride would have prevented the adoption of the A6M Zero.