Considering that you put in SV and an offensive Zygarde set, I'm gonna have to imagine this is natdex ubers because I don't think this thing is in the game. With that in mind, thousand arrows is the superior choice. In fact, in almost every other format, this is the chosen option for the sole purpose of not needing another move to deal with flyers, levitaters, and air balloon. You literally just click one goddamn button to deal with those immune to this move. Resists are another story however
Earthquake is stronger but it's secondary effect of condemning most dig users to death is next to worthless in competitive because dig is almost never used. Thousand waves preventing a switch is nice but you run into that issue of needing another move to deal with flyers and if you have to use outrage, that's not really a compelling case because outrage, despite its strength, is a double edged sword and your side of that sword is massive compared to the opposite side. With how brainless it is to click fking thousand arrows, that is the best move. Just as a side fact, thousand arrows is a huge part of the reason why Zygarde has been banned in both gen seven and gen eight ou. This move is even more brainless to click than knock off or toxic
