Mega Man Star Force 3: Black Ace

Beat the game for the first time.

After you get all 5 Gold Stars, Go back and Fight Crimson Dragon. After you defeat him and watch the credits and cutscences you will recieve a Black Ace Wallpaper that you can set as a background for your Hunter VG.

At the title screen, hold L and press G Comp Star, M Comp Star, M Comp Star, SS Star, G Comp Star, S Comp Star, and Black Ace Star. He'll appear in the Meteor G Ctrl CC, which is located in the Orbital Base.

Collect all the Giga cards.

At the title screen hold L and press these gold stars in order: S Comp Star, G Comp Star, S Comp Star, M Comp Star, SS Star, SS Star, and Black Ace Star. You should hear a confirmation if done correctly.