By accomplishing a variety of tasks, you can unlock new characters to use in the game. Zako A, B, and C can only be used in Vs., Training, and Boost modes; Leopaldon may only be used in Vs. and Training modes.

Effect - Code

Leopaldon - Defeat Leopaldon at level 200 in Arcade mode.
Zako A - Clear Boost Mode once.
Zako B - Clear Boost Mode once.
Zako C - Clear Boost Mode once.
EX Mode Characters - Accumulate 100 points in Arcade mode; now EX mode characters will challenge you randomly (their names will be in red). Defeat them to unlock them.