At the title screen, enter this code: Top C, Top C, Bottom C, Bottom C, Left C, Right C, Left C, Right C, B, A, and then hold down Z and press Start.
The announcer will yell "Goal!" if you completed the code. The result is pretty much the same as every other big head code.
In addition to the six regular groups, there is also a group of all stars. To access this covert group, input this code: Up, L, Up, L, Down, L, Down, L, Left, R, Right, R, Left, R, Right, R, B, A, and then hold down Z and press start. The announcer will scream: "What an incredible comeback!" if you did everything right. Just go to the team selection screen and you'll see a another group of teams, the All Stars.