from gamefaqs....
Euro and World Classics teams:
To unlock both teams, simply complete the league mode in whichever level of difficulty as well as league length(i.e full season or half season). After which save the configuration in the option files and you will be able to assess the two hidden teams.
Euro and World All-Star teams:
To unlock both teams, you will have to complete the International Cup. Similarly, the level of difficulty or game length is variable. After which save the configuration in the option file and you will be able to assess the all-star teams at your own discreation.
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i was sure you could unlock more. its that long since i played the game i dont remember.