From the 'Secret Codes' Menu, enter any of the following codes to unlock the All Madden team:

Unlocked Team Code
1984 All-Madden team Madden84
1985 All Madden Team Mad1985
1986 All-Madden team 86madden
1987 All Madden Team 1987mad
1988 All-Madden team Madden88
1989 All Madden Team Mad1989
1990 All-Madden team 90madden
1991 All Madden Team 1991mad
1992 All-Madden team Madden92
1993 All Madden Team Mad1993
1994 All-Madden team 94madden
1995 All Madden Team 1995madn
1996 All-Madden team Madden96
1997 All Madden Team Mad1997
1998 All-Madden team 98madden
1999 All Madden Team 1999mad