I'm using it similarly to Rhyperior RNFor Rhydon I would suggest a Rock move like Stone Edge or Rock Tomb to lower Speed on foes, for Sandstream under Dynamax, with Fur Coat or Ice Scales. 508 Defense after Eviolite with a neutral nature is just bulky enough off of 414 HP to not require Fur Coat, which means that 310 SpD from Eviolite (+ Sandstream = 465) is very much going to make a huge difference for whether you want to use Ice Scales or Fur Coat.
Special Attackers are pretty limited this generation, so I think Fur Coat works better. Plus, if you need Special Defense, you can just summon Sandstream via Dynamax and keep Fur Coat.
My tip is to consider its typing. Technically, you could also run Prankster and Electrify to block Zacian, and Zamazenta from using moves against it as it’s a Ground-type.
Rhydon @ Eviolite
Ability: Intrepid Sword
EVs: 252 HP / 252 Atk / 252 Def / 252 SpD
IVs: 0 Spe
Prankster+Electrify tho is not useful imho. Yeah, I block their moves, but the second I try to do something else i get bopped, since Rock dies to Steel (and Fighting, damned body press XD)
Ice Scales is almost useless. There are like 4 special mons in the meta. Reshiram, Mewtwo (with psystrike), Eternatus. And Darmanitan-Zen that mainly uses special attacks to counter Zacian. But they are really not in every team, so I found that IS is useless like 4 times out of 5.
I think I won't try to create a decent team until Zacian (and possibly Zamazenta?) get out of the meta. So many mons and strategies are literally useless with 2-6 Z-doggos in the enemy team.