Whoops, you are correct. SII has four more playable characters than SI though it's really only by one since a few characters are impossible to recruit in one file like Kasumi and Valerie. SI and III are tied for the second most playable characters at around 76 playable ones. SIV has the smallest playable cast ranging around 60. Though if you drop the non-Stars from both lists, SI has the most playable stars of all the entries.