So obviously this is WAI, but I did think of a way that might make Nihilus fun in GW, but A) haven't tried it yet since I'm saving GW for tomorrow, and B.) it's probably less efficient than normal GW strategies.
But my idea was to pair him on easy nodes with characters who us non-attack abilities (defense up, heal, etc.) so he can get annihilate off. Annihilate several tanky characters along the way. By 12, he would have a sith lord of health. He would still need good supports since he's so slow, or else it will just be five toons wailing on him forever. Again, probably not worth the effort vs. normal GW strategy, but could be fun.
P.S. "Bee" colon is not supposed to be a sunglasses face.