Unlock ZZ Gundam
Buy E Route and beat it. Then buy F Route and beat it with a One Year War Character (Amuro Ray). Then beat Psyco Gundam and Psyco Gundam MKII in A Route. After that, buy Psyco Gundam and Psyco Gundam MKII. After Buying Item No. 1, 2, 4, 6, 8, 9 in the specials section, Gundam ZZ will be available for purchase.