Shoutout to Sevon for helping with this page.
Reducing the party to 0 people
The basic method is to complete The Last Megalith or Last Battle while town scenarios are available on the world map, then start a new game using the clear data and select any town scenario.
Note: the bar in Westia is a good spot to use
Alternatively, during a main character replacement event, the new main character is placed into a sub-party in advance. There should be no more than four members after the replacement. A good place to do this is with Showdown! Alexei and Wil vs. Egg.
Also, if you make 193b=4 and leave Westia, the main character becomes Tyler in the event, so it’s possible to have a party of four where Tyler isn’t the main character.
If you open the equipment menu for the main party with 0 people in it, you’ll see that the main party is in a state with 0 people. A buggy character appears, who’s name is Nebelstern, and all stats are set to 0. You can equip this character with arts and spells, but the equipped arts and spells won’t disappear even if you reset them and won’t return even if you load them.
If you have two save files that have the 0 people party bug active, you can transfer items via bug transfer. Techniques can be learned in the same way. Tech learned in one save file can be sealed in the other to be learned.