If I remember right(on phone and to obnoxious to look) standard is how many they have by default. The plus means that's how many you unlock playing different courses in Tima attack, Arcade and survival.
along these lines)
Kasumi 2 standard +2 story +ATS(arcade/time/survival)
Sandard, starts with 2. Story, unlock 2 during the story(near the end). 2ATS play arcade time attack or survival(2 different courses needed)
Its something along hose lines. I'm not sure if I'm discribing it well >< I'm just going off memory on what his post looked like and my understanding merging with it