Saying the R8 classes doesn’t have synergy with Wugushi is pretty funny because every class has synergy with Wugushi.
Wugushi skills can be used mounted (besides gu pot) and with any weapon. The damage from Wugushi is essentially unavoidable due to being a DoT, the skill animations are super short, and the cool down is long enough to use whatever you want inbetween without having skill rotation issues. These are the biggest asset to Wugushi but it seems like a lot of people do not think about these more subtle qualities.
I mean, what other things do you want from Wugushi?
Other than Wugushi, you have scout1/falconer -> musket/cannon. Scout 3. SR2. Maybe fletcher 3, but i wouldn’t go Fletcher with QS