Core members of big groups

For BLACKPINK, literally all of them, but I’d go with Jennie the most.

For Stray Kids, it would be Han, Chan, and/or Seungmin.

Blackpink without one member is not Blackpink. They complement each other very well.

Quote from bartkun

As for WJSN musically if they would lose Exy they would lose the producer/rapper, but I think that people would have harder time to accept WJSN without Seola, Bona or Luda

Exy, Seola, Bona or Yeonjung if it was about the song.

for the second part, I think it would be Eunseo or Dayoung...

core members you say?

taeyeon, sunny, tiffany, yuri, yoona, sooyoung, seohyun, hyoyeon

soyeon, yuqi, minnie, miyeon, shuhua

sakura, chaewon, kazuha, eunchae, yunjin

seems very core to me!!!

Of course they all contribute, but I think it's Seulgi in Red Velvet. Because she usually carries the group in terms of dance. Wendy also does most of the adlib in their title song. All on Shinee, because they're an allrounder group. They do everything in dance, vocals and rap.