MLB Slugfest 20-04:
Enter these codes when the match-up screen appears as your game is loading by pressing Square, Triangle, and Circle the required amount of times shown in the Parenthesis (#) below. Square changes the first position, Triangle changes the second position and Circle changes the third position. Also make sure to press the direction listed after inputting the code. 

Example: For No fatigue press Square 3 times, Triangle 4 times, Circle 3 times then Up 

No Fatigue: 3-4-3 Up
No Contact Mode: 4-3-3 Left 
Unlimited Turbo: 4-4-4 Down 
Bone Bat: 0-0-1 Up 
Blade Bat: 0-0-2 Up 
Maximum Speed: 0-0-3 Left 
Ice Bat: 0-0-3 Up 
Mace Bat: 0-0-4 Left 
Wiffle Bat: 0-0-4 Right 
Log Bat: 0-0-4 Up 
Spike Bat: 0-0-5 Up 
Maximum Power: 0-3-0 Left
Little League Mode: 1-0-1-Down 
Dolphin Team: 1-0-2 Down 
Dwarf Team: 1-0-3 Down 
Minotaur Team: 1-1-0 Down 
Tournament Mode: 1-1-1 Down 
Scorpion Team: 1-1-2 Down 
Gladiator Team: 1-1-3 Down 
Sub-Zero Team: 1-2-2 Down 
Extra Time After Plays: 1-2-3 Up 
Rodeo Clown Team: 1-3-2 Down 
Bobble Head Team: 1-3-3 Down 
Small Heads: 2-0-0 Left 
Big Heads: 2-0-0 Right 
Pinto Team: 2-1-0 Right 
Evil Clown Team: 2-1-1 Down 
Horse Team: 2-1-1 Right 
Eagle Team: 2-1-2 Right 
Lion Team: 2-2-0 Right 
Oshlan Team: 2-2-2 Down 
Todd McFarlane Team: 2-2-2 Right 
Rivera Team: 2-2-2 Up 
Alien Team: 2-3-1 Down 
Napolitano Team: 2-3-2 Down
Casey Team: 2-3-3 Down 
Softball: 2-4-2 Down 
Rubber Ball: 2-4-2 Up 
Maximum Batting: 3-0-0 Left 
Extended Time for Codes: 3-0-3 Up
Midway Park Stadium: 3-2-1 Down 
Atlantis Stadium: 3-2-1 Left 
Empire Stadium: 3-2-1 Right 
Rocket Park: 3-2-1 Up 
Monument Stadium: 3-3-3 Down 
Forbidden Stadium: 3-3-3 Left 
Terry Fitzgerald Team: 3-3-3 Right 
Coliseum Stadium: 3-3-3 Up