Forgive my newness but what legal reasons?
Uri Geller a self proclaimed psychic tried to sue Nintendo for 60 million Pounds in 2003 by saying that Kadabra is an unauthorized parody of himself. As a result the issue hasn't been resolved 13 years later and until it is we won't have any new Kadabra cards.
There also the issue with some people thinking the star and markings on Kadabras body are the SS symbols used by Nazi Germany.