We need to settle this before it becomes a full-fledged battle.
Has Butters become so popular and frequent that he can actually be considered one of main characters?
I say... well, there's a gap between how much screen time a character has, and how 'main' a character is. SKCK have been together as four friends, four main characters, side by side, since the very, very, very beginning. They're the ones who sing the theme song, they're the ones that stand at the bus stop. They also, as tons of people have pointed out before, fit the four temperaments together to a T. Butters wasn't there for any of that. Maybe it sucks, maybe he deserves to be, but he just kind of isn't.
On the character portal, I keep removing Butters from the list of main characters, but I'm afraid someone is going to keep putting him back. We have a 'major characters' section now, isn't that enough?
So what. Is Butters a main character?