Fantasy Teams and Stadiums:
At the Title Screen or the Main Menu press Y, X, R to unlock all Fantasy Teams and 
Fantasy Stadiums.

Cheat Codes:

Enter these codes at the versus screen: 

Unlimited Turbo: X, X, X, X, Y, Y, Y, Y, B, B, B, B, DOWN 
Softball Mode: X, X, Y, Y, Y, Y, B, B, DOWN. 
Ball Is Rubber: X, X, Y, Y, Y, Y, B, B, UP. 
Max Out Speed: B, B, B, LEFT. 
More Time After Each Play: X, Y, Y, B, B, B, LEFT. 
Big Heads: X, X, RIGHT. 
Tiny Heads: X, X, LEFT. 
Max Out Batting: X, X, X, LEFT. 
Max Out Power: Y, Y, Y, LEFT. 

Lions team:
Hit a home run at Comerica park with the Tigers.

Sub Zero team:
Hit a home run at Midway Park.

Fantasy team equivalents:
The following is a list of Fantasy teams and the real teams that each corresponds 
to.

Lions: Houston
Horse: Philadelphia
Pinto: Atlanta
Eagles: St. Louis
Gladiators: Boston
Bobble Head: Toronto
Dolphins: Florida
Scorpion: Arizona
Sub-Zero: Seattle
Evil Clowns: NY Yankees
Minotaur: San Francisco
Alien: Minnesota
Casey: Chicago Cubs 

Extra time after plays:
Press Left, X, Y(2), B(3) at the versus screen. This mode allows you more time to 
beat up other players.

Bobblehead team:
Hit ten home runs in a game.

Eagles team:
Get walked three times in one game. To do this easily requires two controllers. 
Use controller two, choose any pitch, but throw a ball.

Scorpion team:
Hit a home run with Sub Zero at Midway Park.

Atlantis stadium:
Hit a home run at Right Field in SBC (San Francisco) 

Coliseum stadium:
Hit a home run at Fenway (Boston Red Sox)

Empire stadium:
Hit a home run at Yankee Stadium (New York Yankees) 

Forbidden stadium:
Hit a home run at Pet Co (San Diego Padres) 

Midway stadium:
Hit a home run at Wrigley Field (Chicago Cubs)

Monument stadium:
Hit a home run at Citzen's Bank (Philadelphia Phillies) 

Rocket Park stadium:
Hit a home run at Minute Made Park (Houston Astros) 

Easy home runs:
Press Power Swing. This works well in the homerun derby.