So who do you think are the real main charaacters of Deltarune? The wiki listed Ralsei and Susie as "deutertagonists" and Noelle as "tritagonist." I edited Ralsei's title to "tritagonist" and Noelle was changed by someone else to "tetartagonist" (basically the fourth most important character) before those changes were reverted due to being "controversial."
I myself fail to see how Noelle is a tritagonist. She is important, but Ralsei is the third member of the team comprising the main characters of the game - hence, he is the third most important character.
We had a pretty long discussion on this in the Discord and we agreed that Susie and Ralsei shouldn't be ranked in importance above one or the other, and that any organizations below deuteragonist were too much. (We couldn't even find a source for "tetartagonist" existing.)
Just putting my two cents in here since I kinda started that discord discussion, I feel like these formal qualifiers of "character importance" (including "protagonist") are unnecessary. I feel like describing Kris, Susie, and Ralsei as "main characters" is apt, and putting Noelle there is probably justifiable too even though she isnt as directly active. These four are who are currently in https://deltarune.wiki/w/Category:Main_Characters which is linked from the main page.