Reuniclus can run a multitude of sets, but if I'm being honest I don't think this one is viable. You're probably better off trying Flame Orb or Sticky Barb if you're looking to cripple the opponents with swapping items, its not exactly like Reun benefits much from outspeeding Pokemon, that's not really its purpose in the meta.
If you insist on using this set, I'd pair it with Pokemon that can handle special walls that can take on this set. Answers to Blissey and Tyranitar make for good partners, so Urshifu and Rillaboom would be good.
Here is an analysis that mentions even more teammates for Reuniclus, while also discussing its best set