EX fighters
Defeat an EX character in survival mode. Then, hold L2 when choosing that fighter at the character selection screen to play as the EX version.
SP fighters
Defeat an SP character in survival mode. Then, hold L1 when choosing that fighter at the character selection screen to play as the SP version.
GGX and GGXX mode
Successfully complete 70 missions to unlock GGX and GGXX mode.
Play as Kliff
Successfully complete 50 missions to unlock Kliff.
Play as Justice
Successfully complete 50 missions to unlock Justice.