As far as I am aware the Watchers are close to featless, they are more like the old Guardians supposedly very powerful but do jack shit for fear of interfering. Current Guardians are a bunch of nutters.
Apart from Mandrakk and anti-monitor what has monitors done to show their power level?
Also Watchers arent featless they have feats, mostly defensive or BFRing people but still not entirely featless.
There are few awesome feat from Aron the Rogue watcher if that is helpful.
I would say Monitors should eventually win just by virtue of the fact they can actually attack their opponents here.
However, the Watcher has, on occasion, defended himself effectively from attacks, so I don't know that it would be quick or easy, especially as I don't recall any of the Monitors having especially impressive offensive powers. In Countdown they actually seemed rather feeble. Wasn't Monarch's army slaughtering them?