So this character and the partner I have planned for her were originally a PC/NPC duo from a Pokemon Tabletop United game. While it was based on Pokemon as an existing property, the setting was a unique medieval fantasy one, with no reference to any canon events, although the legendaries did exist. Would I need to rewrite their preincarnation backstory to not include Pokemon at all, or would they be fine? (I have the original DM's blessing to play their NPC as well.)

Also, for combo apps, do they have to share an account as well, or can they have separate accounts?