Seungkwan (SEVENTEEN) and JooE (Momoland) have claimed to be rivals on variety shows, but they're also really good friends. Also Mingyu (SEVENTEEN) is friends with Eunwoo (ASTRO) and Jungkook (BTS), there's also a '97 line chat, which includes '97 liners from Seventeen, BTS, Got7, and others. And Hoshi (SEVENTEEN) is apparently great friends with Key (SHINEE) he said he's come over to his house several times, and Hwall (THE BOYZ) has a brother-like relationship with Jimin (BTS) because they were both in the same dance studio in Busan, Woozi (SEVENTEEN) is also good friends with Kang Daniel, because they're both from Busan. MONSTA X and SEVENTEEN are best friends as a whole because they debuted at the same time. There's more but I don't want to make this post any longer than it already is