Okay here's what I'm thinking, Matt has less destructive power than X does at this point, but has more control and is more calm, making him able to think of a plan to subdue X (Not kill, cause they're friends) He would probably be able to break down his abilities in due time like he did with Mars(Source: WTUD Chapter 5), and if things get tough he'll use Ares armor.
TL:DR: Matt