How to make a Class System
So, you want to make a class system? Well, there is no built in feature to have a class system. But, there are different ways you can go fake one with or without plotscripting.
The best way to create a class system is to use a chain of text boxes to manipulate the party. First you have to create a set of heroes as well as a blank "selection hero" that the player will be until they select another character (make sure this character is the Starting Hero in the New Games settings menu, which is hero 0 by default). The reason for this is that each hero will act as a different class(you can add other options such as race, gender, etc but each one will have to be another hero). Once you have created your heroes you need to create an NPC that starts your chain of textboxes, place the NPC on the same tile that the hero starts on and set it to activate on step.
Next, open the the first text box and write "Who do you want to be?" (You can put whatever you want here this is just an example) then chain that textbox to another via the conditionals menu (just set the "after" tab to always jump to the next textbox). Now you can make a textbox for each hero you have including the one that the first textbox automatically jumps to. Then go to the tags tab and name tag two "select". Now go back to the second textbox you created and add two options "yes" and "no".
Make the "yes" option turn tag 2 on and the "no" option turn it off, and repeat this for each of the textboxes other than the first one you created. Then set the "after" tab in the conditionals to jump to the next textbox in line when tag 2 is turned off (the final should loop back to the first for instance if you have textboxes 1,2,3 and 4, number 4 should loop back to 2). Finally assign a hero to each of the textboxes and put that hero's name in the display text of that box, and in the "party" tab of the conditionals set that hero to be added to the party when tag 2 is turned on.
And now the system should work. Remember that the blank hero will still be in the party once an actual hero is selected. You can remove this hero with another NPC placed later.
Another option you can do without plotscripting is to make the game begin in an area where you can select heroes on a map. For an example, see Fenrir-Lunaris's game, Final Fantasy H. It is a perfect example of this style. In the game, there is a line-up of heroes on a dark map. You are a white hand, and when you talk to a hero, you have the option to select that person. There are four classes, Cleric, Warrior, Thief, and Black Mage, and four races, humans, elves, dwarves, and anthros. You could try doing something similar, or like just like it.