Persian and Purugly are also good candidates for other assisters. Persian gets technician on the dragon tail, purugly has decent attack, and they're both damn fast. For the weavile set, it would be worth adding Thief for a decently strong STAB attack.
Ambipom gets technician covet, so essentially a 90bp attacking move.
Smeargle or Giratina with destiny bond are probably the best dragon tail users
Another idea would be giving leftovers to reperadusu (on a single cat team for better luck), and setting up hail or sandstorm. Have reperadusu protect every other turn, and not only will the team suffer 32 dragon tails, but they'll also suffer 64 turns of sandstorm damage.
Mew gets both Trick and Dragon Tail, so it would be a good candidate for the dragon tailer. Same goes for smeargle. Trick a scarf onto some hapless pokemon.
Finally, your average erufuun or genie won't invest heavily in speed, and there's no reason not to give reperadusu a 252 speed EVs and a jolly nature, which I think will allow it to outspeed the aformentioned threats (correct me if I'm wrong though). In fact, reperadusu is so fast that the only priority attacks that will be hitting it are Extremespeeds, weavile's ice shard and infernape's mach punch (and the whole nature thing still comes into account)