Unlock All Venues:
On the Main Menu, select My Corner and enter the following:
Left, Left, Left, Right, Right, Right, Left, Right, Right.
Big Heads:
On the Main Menu, select My Corner and enter the following:
Left, Right, Left, Right, Left, Right, Left.
Unlock Big Tigger:
From the Main Menu, select My Corner, Record Book, Most Wins-Boxer, then press Up twice.