Do I need Oceans GMDSS

Hello. So I get all kinds of different answers when it comes to going more than 200 miles offshore. Some people say as long as there’s someone onboard that has Oceans and or someone has GMDSS But I’ve also been told any watch stander has to have both. I tried looking this up. But I’m not very good at finding the real answers Thanks

See 46 CFR 15.1103(a) and 15.817.