Beach Stadium
Select "Homerun Race" mode, then press X, Circle, Triangle, Square on controller two at the stadium selection screen.

Oldboys Team
Select "Homerun Race" mode, then choose "Single Play". Then, press X, Circle, Triangle, Square on controller two at the team selection screen. The Oldboys will now be selectable.

Oldboys Team in Team Edit Mode
Press X, Circle, Triangle, Square on controller two at the uniform selection screen. The Oldboys will now be selectable.

Sea Stadium
Select "Homerun Race" mode, then press Square, Triangle, Circle, X on controller two at the stadium selection screen.

Sky Tower Stadium
Select "Homerun Race" mode, then press X(2), Circle, Up, Circle, Down, Triangle, Square on controller two at the stadium selection screen.