Well most of those forums don't really go into depth for what the characters can do like we do on this site. Also Zack wouldn't be a good match for Noctis either. Everyone in FF7 is
getting this which gives them a far better hax advantage. Also Sephiroth is currently the only FFVII character that's useable right now since the other profiles have yet to be updated with the Spiritual Energy stuff. Cloud, Tifa, and Vincent's profiles are being worked on though.
Noctis needs a revision though so we'll see. Currently the best bet for an in-verse match against Noctis would probably be
Terra. Firion and Luneth are also options like I mentioned. Sephiroth is just too much for Noct to handle.