@Combos: You guys are forgetting about the one rainbow attack that you get when combining Fire Oath and Water Oath that increases the chance of secondary hits happening. If it doubles the chance allong with Serene Grace, Dunsparce's Rock Slide will always flinch all of your opponent's Pokemon, provided it hits. If it only increases it by another 100% of the chance, like I suspect it will, it will have a 90% chance to flinch them or 81% when you factor in accuracy.
Granted, Dunsparce can only outrun positive Base 100s with a Choice Scarf and no other Pokemon can get a move with that high of a flinch rate with Serene Grace that hits all opponent's Pokemon, but it's something to think about.
@Entry Hazards: In order to actually stop some of the use of entry hazards you have to be able to gain something from your opponent using them. Rapid Spin or an auto-Rapid Spin Ability wouldn't work, even if they hit Ghosts, because you're not actually doing anything to your opponent and they can still get a free switch-in to the Rapid Spin.
IMO, Spikes aren't really broken and Toxic Spikes is nearly useless with all of the Steels, Fliers, and Levitaters in OU, so SR is really the only problem. Someone suggested giving Rhyperior an Ability that would shoot back Rock Attacks, which would work but I have simpler idea; make a Rock-type Volt Absorb. This would give you a free 25% HP boost whenever you switch in and clear the field of SR, provided your opponent set it up.
They could potentially give this abilty to Regirock through the dream world and give Regice and Registeel some sort of similar abilities. The only reason I would normally be against doing something like this is that Legendaries always have one ability but since the dream world is giving second abilites to starters and Eeveelutions, it could work.