The heart of Mario Superstar Baseball is the Challenge Mode. It is a single-player mode where the player selects a pre-built team and must defeat all the other teams; at first Bowser's team is the last team to beat for the cup, and must be unlocked before the player can use him. There are six teams, each led by one of the Captains (Mario, Peach, Yoshi, Donkey Kong, Wario and Bowser), features a secondary captain (Luigi, Daisy, Birdo, Diddy Kong, Waluigi and Bowser Jr. ), and is filled with a mix of sub characters, some of which are duplicated within a team, but do not appear on any other team. For example, aside from the aforementioned captains and sub-captains, Mario's team consists of Monty Mole, 3 Piantas and 3 Nokis, Princess Peach's team consists of Toadette, Toadsworth, and 5 Toads, Wario's team consists of Boo, King Boo, Petey Piranha, and 4 Magikoopas, Yoshi's team consists of Baby Mario, Baby Luigi and 5 Shy Guys, Donkey Kong's team consists of Dixie Kong, Goomba, Paragoomba, 2 Paratroopas, and 2 Koopa Troopas, and Bowser's team consists of 4 Dry Bones, Hammer Bro, Fire Bro, and Boomerang Bro (although Hammer Bro, Fire Bro and Boomerang Bro are separate characters (enemies) in the Mario series, in this game, it is actually just a color variation of the same character. ). Players challenge the other teams, beating the other four opens the path to Bowser's castle. The secondary purpose of defeating other teams is to recruit other characters to improve ones team. On opposing teams, each character has a set of scouting flags. During the game players will have mission objectives like "Strike 'em out", or "Score a run", that earn flags; if one gets all the flags of a particular character and wins the game, that character will be recruited. If the player fails to complete a mission, he/she must wait for a while to complete another mission. Flags are cumulative, so if the player doesn't get all the flags in a game, or loses the game after getting all the flags, the flags earned will remain when the team is challenged again; a team can be challenged as long as the captain of the team is not recruited. Players of a different color can't be recruited and can only be played in minigames and playing with the teams they start on.