User blog comment:Omega natsu2/Future Matchups!/@comment-4829046-20140414155741

Mavis Vs. Zeref is already a thing so...

Mavis Vs. Acnologia. Technically it already happened with Mavis basically blocking his attack

Zero(unharmed version) Vs. Gildarts P.S. Unharmed means that he wasn't beaten up while in Brain form or in other words, was never sealed.

Zero(unharmed version) Vs. Hades(younger version, as in, without artificial heart)