No, I didn't bother listing it anyways since you didn't list the Dark Horses. Keep the alt, just list the mons

I haven't played any battle with my alt yet, but I posted my sign up before making my team. Should I choose a new alt anyway?

If you didn't start the team on PS, then sure. You just need a fresh alt every time the Dark Horse roster changes, but if you didn't use the team on Showdown yet, then the point is moot.

I just finished my team for Dark Horse proyect right now, but finally I added two more dark horses to my team. Obviously I didn't start on PS, so can I update my sign-up?