In arcade mode level 100+, Ex characters will challenge you. Defeat them to unlock them.

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.

Play Scramble in RK II Factory under the normal difficulty setting. Finish the last stage with a score of 1,500,000 or greater. Robo Ky II Substance will appear. Defeat him to unlock Kakusei Sol and Kakusei Ky.

Defeat Leopaldon at level 200 in Arcade mode.

Robo Ky II EX version
beat boost mode in AK II factory

Zako A
Clear Boost Mode once.

Zako B
Clear Boost Mode once.

Zako C
Clear Boost Mode once.

In arcade mode level 199, defeat Leopaldon to unlock him.

First of all, you have to have Ky and So's Ex versions unlocked. Play Robo Ky II's Boost Mode on Normal difficulty, and beat Stage 5-E (Last Dance) with 1,500,000 points or more, and a giant Robo Ky II will appear. (Robo Ky II: Substance.) Defeat him to unlock Kakusei Ky and Kakusei Sol. Select them by highlighting Ky or Sol on the character select screen, and press Start twice.

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.

In GGBoost, defeat Kakusei Sol and Ky in the last stage to unlock them.