Boss challenge mode becomes available under the following two conditions. Both hidden Bosses (Ultimate Rugal, Shin Akuma) must already be defeated and unlocked. Hold X + Y and press Start while highlighting arcade mode

Clear Boss challenge mode with no continues. The "Extra Option" becomes available in the game

Hold Start + FP after winning a stage to make your character say an opponent specific quote. Hold Start + FK to make the character talk with a team member

Defeat all characters in survival mode