User blog comment:James12708/Reapers VS. Forerunners VS. Angels from Darksiders VS. Humanity from Halo VS. Council and humanity from Mass Effect VS. Imperium of Man/@comment-4967682-20130116065115/@comment-4967682-20130116203419

I would give them a good chance against even the Covenant. The UNSC held the Covenant back for 27 years with a tiny number of primitive ships. The more advanced and infinitely more numerous Council might be able to beat the Covenant through attrition and dirty tricks.

As for the UNSC: the salarians alone could easily defeat them, no matter the era.