Complete Story mode to unlock an alternate costume with the following characters. If available, the next alternate costume for that character will be unlocked when Story mode is completed with them again.

Ayane C3, C4, C5, C6
Bass C3, C4
Bayman C3
Brad Wong C3
Christie C3, C4
Elliot C3, C4
Hayabusa C3, C4
Hayate C3, C4
Helena C3, C4 C5
Hitomi C3, C4, C5, C6, C7, C8
Jann Lee C3, C4
Kasumi C3, C4, C5, C6, C7
Kokoro C3, C4, C5, C6, C7
La Mariposa C3, C4, C5
Leifang C3, C4, C5, C6, C7
Tina C3, C4, C5
Zack C3, C4

Complete Time Attack mode on the default settings to unlock an alternate costume with the following characters. If available, the next alternate costume for that character will be unlocked when Time Attack mode is completed with them again.

Ein C3, C4
Genfu C3, C4
Leon C3, C4
Spartan-458 C3, C4, C5, C6, C7