3.
Never go to your party roster screen the entire game. When forced to, quit out immediately. Only one non-generic char can be used at a time.
I'd dare say this is literally impossible. This is basically saying that the entire game you have to use starting equipment, starting skills (Wish, Dash I think?), and inability to advance jobs or buy any skills or anything. A lv 99 ramza, with no skills, the inability to use items in combat, combined with weakest armor in game, is worthless. With or without a single non-generic char, you wouldnt even get to Mustadio or Agrias (who would be only slightly less weak to help you get to Ch 4., considering only using Stasis Sword + mustadio doesnt start with anything either pretty much)

The execution site.
All the zodiac fights
Fighting Izlude and Wiegraf in Orbonne
Wiegrafs fight in Riovannes...

etc. Basically any major storyline battle past Ch 1

Obviously if you actually managed to get Orlandu then it wouldnt be a challenge anymore, but I'd love to see someone actually get to Orlandu