Slam 'n Jam '96 (PSX)

Small players:
Choose your teams and go to the scouting report screen for the home team.
Highlight the continue option and press X. Next, you'll see the scouting
report for the away team. Now, press X and press R1 button rapidly until
tipoff. Press Start and then press Start again. Every player will now be
about half the size they normally are.

Big head code:
Choose your teams and get to the scouting report screen for the home team.
highlight the continue option and press X. Next, you'll see the scouting
report for the away team. Now, press X and then press the L1 button rapidly
and repeatedly until tipoff. After the tipoff, press Start and then press
Start again. the players will have huge heads.

Shot percentage code:
Choose your teams and then get to the Scouting Report Screen for the home
team. highlight the continue option and press X. Next you'll see the
scouting report for the away team. Now press X and hold down the L1 button
until tipoff (instead of pressing it rapidly). You'll see the player's shot
percentage on the screen.