Few things, T-Wave over Toxic on Xatu is generally better.
For Venu the best EV spread would be..
EVs: 212 Spd / 252 SAtk / 32 HP / 12 SDef
This hits 272 so you can outspeed random Scarfmie. You can go more if you want, but i usually chuck the last 12 into SpDef for more bulk. Also hits a xx9 HP number for minimum LO damage.
HP rock is quite uselss on Ninetales, I'd recommend Pain Split or Roar in its place.
Your EVs on tales are also bad as you miss the lefties number, and an extra SpD stat since you hit xx9.
EVs: 44 Spd / 252 SDef / 200 HP / 12 Def