How about Onyx-Bacdafucup. Strictly hip-hop, strictly hardcore. They came out at the same time Mobb Deep who's sound and style was similar but I think it was M.O.P. who probably mirrored them the best. That unique way they'd spit so that all 3 would finish a verse together. There aren't really any popular rap GROUPS anymore. There are occasional collaborations but Slam, Shiftee, Throw Ya Gunz and some others will still get the boys jumpin' in the club.