Offical Baseball Rules (WBSC)

FORFEITED GAME
7.11
A game shall be forfeited only as a last resort in favour of the team
not at fault in the following cases:
7.11.2
If, after the game has started, one team refuses to play

7.11.6
A game shall be forfeited to the opposing team when a team in
unable or refuses to put nine players on the field.