To unlock the minigame version of Baby for use in the main game, play each minigame at least once. If you've forgotten which games you've already tried, the game displays a play count on each minigame. After playing each minigame once, you need to play one more minigame of your choice so that the game will save your stats. Baby Robo will now be available in the main game. Note that to select Baby Robo, you have to highlight Baby on the character select screen and press 1.