P.S.: I did not include the most obvious ones (i.e. Kenny, Clyde, Butters, Randy and Ike) because the margin of rivalry against Cartman isn't as narrow as everybody else.

I'd say Nichole. She seemed supportive of his and Kyle's "relationship" in "Cartman Finds Love," and from what I can recall I don't think she ever ended up finding out that Cartman was the one who tried to get her and Token together. I think out of these choices, she's the one who has interacted with him the least.

I was thinking Stan, but Nichole out of these

In “Dead Kids” Cartman confronted Nichole about her and Tokens relationship and she was relatively polite to him

Nichole never seems to act that antagonistic towards him. She seems to be a very nice girl.

I think Nichole doesn't hate Cartman as much as the others on this poll. They haven't really interacted and the few times they have, she was relatively neutral.

Nichole is a sweet girl and I think she's the SP character I'm the most similar to