Veronica is definitely Fe ego and Archie Andrews seems LSI. Their relationship is typical beta, and with Veronica's expert manipulation she's def EIE(I'm open for ESFj though).
Jughead and Betty's relationship is quite Delta I think, but Betty is very much IEI with certain situations or people bringing out her edgier darker side. She likes the danger and wants to be part of it e.g. joining the Serpents. I think that's why she's drawn to Jug?
Sheryl (or is it Cheryl?) is a typical 3w4, and probably Se valuing.