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.

Beat Rogue ZZ.

Collect all the Standard cards.

Beat Sirius Sigma, Moon Destroyer Sigma, and Apollo Flame Sigma.

Beat Sirius.

Beat Acid Ace BB or Grave Joker RR.