You can optimize the stats of any playable character that stays with the party until Disc 4.
A couple of characters have special variations: Eiko can achieve very high stats by exploiting a glitch in the game, and Quina can be made into either a physical fighter or magic user. You can choose these variations here. Other character and gameplay options, such as absorbing forced experience or doing a speed run, will be available in the next step after you click "Continue". For more details about these variations, see section 3.3 of the Perfect Stats Guide.
The calculator can't directly calculate for balanced Quina. To calculate optimal stats for balanced Quina manually, see Calculating balanced Quina.