The only one that is confirmed to be able to beat Nihilus with his eating ability that we know of is Exile. Do we know that, for sure, his powers are unique, or that Ancient Sith Magic can't counter him? No, but it's a viable assumption.
I'll have to assume that his Force Feeding would be unbeatable by all that aren't a "wound" in the force a la Exile.
here does this make sense
exile=empty glass
glass=the embodyment of the force
the force=water in glass
nihilus=instant evaporation
nothing can't be evaporated and water can but water can't just refuse to evaporate it just happens.
just because someone has more water (like ragnos) doesnt mean that it can't be evaporated just the same as someone with very little water