To unlock Pac-Man in Super Smash Bros. Ultimate, start by playing the game and completing a series of battles. First, ensure you have progressed through the initial stages of the game. Then, navigate to the "Smash" mode and select "Classic Mode" or engage in "Smash Battles" to encounter Pac-Man. Once you defeat him in battle, he will become a playable character. For a more straightforward approach, you can access the "Challenger Approaching" feature by playing regularly. To enhance your gaming experience, explore different ways to play pacman and enjoy his unique abilities in the game.