This page explains in detail the interactions between the Baseball (Nintendo) series and the Mario series.
Baseball (Game Boy)[]
Baseball USA Mode teams.
April 21, 1989
Baseball (Nintendo)
Mario
The Game boy version of Baseball features two modes: Japan mode and USA mode. The only difference between them is in the name of the players, and their captain in USA mode are called "Mario" and "Luigi", so they can be assumed to be the Mario Brothers even though they look identical to other players and don't seem to have moustache.
In the international version of the game, however, the pitcher is shown on the cover to actually be Mario.
Baseball Japan Mode teams.
Baseball japanese cover.
Baseball american cover, featuring Mario.
License[]
Copyrights for both series are held by Nintendo.