The player gains Experience Points throughout the game by participating in fights. Accumulating XP allows the player to level up, unlocking new equipment and advancing in the story.
The main sources of experience are tournament fights, challenge stages and storyline fights (boss battles and bodyguard fights). Other sources of experience are survival mode and duel modes, though provide barely any experience, and are an unreliable way to gather experience.
After player reaches level 52 the maximum level, the XP bar is replaced with the word "Max".
Here is a list of all the levels and the XP required to reach them.