Master Mundi distracts Snoke by asking him "What about the droid attack on the Wookiees?" and slices him in half whilst Snoke is trying to comprehend the true genius of Prequel Memes.
In all seriousness though, Snoke's raw strength in the force is amongst the greatest seen in the new canon with how easily he slapped around someone with as much plot hax as Ma-Rey Sue. The only real cap we have on where he ranks is that he should be below Pre-TROS Palpatine by virtue of being created by him, though even that tier would be too much for Mundi. Ki Adi Mundi could defend against a lot of his force abilities with his lightsaber and win if he's capable of getting close, but the odds favour that Snoke would find a way to get past his defences.