NDUU is currently is a solid spot right now so its understandable to take a look at potential unbans. That being said Rain's unban does not add diversity to the tier.



This core alone is already going to be incredibly frustrating to prepare for as Pelipper and Swampert are already incredibly strong Rain pivots to enable Archaludon, who in turn mauls all of the "typical" Rain checks such as Slowbro and Tangrowth. Mons such as Hippowdon and Tyranitar just simply do not win against it head on either as Dragonium Archaludon can wipe Hippowdon off the map at +1, while Tyranitar gets Body Pressed or Aura Sphered to also lose long term. Common bulky grass types like Mega Venusaur and Hydrapple have major flaws into rain such as Venusaur having its recovery stunted due to the weather and Hydrapple hating the Dragon typing more than ever because of Archaludon and Mega Swampert's Ice Punch coverage. You mention Rillaboom sweeping rain bar the Flying and Dragon types but threats in question are so insanely powerful under rain that Rillaboom can't be a long term answer either. Rain guys such as Salamence, Galarian Moltres, and again Archaludon forces both sides to engage in very uninteractive trade wars. If none of the rain checks can actually shut it down fully, that means you most likely need to overcompensate via check stacking.
Consistently checking this core alone puts unnecessary strain on the metagame as a whole. Throwing in the other 3 team slots into the mix for yet another Rain Wallbreaker such as Keldeo, Barraskewda, Kingdra, Basculegion-F, or Hurricane spamming, or whatever flexible utility Rain needs to be powerful just makes me wonder why I'm bothering to bend overbackwards trying to check rain and its multitude of variants when the tier was fine before it.
Damp Rock ban allows people to run out the clock faster but it doesn't make rain balanced. All the checks are still shaky, the constrain still remains. Rock bans are primarily focused on by tiers who use manual setters.



This core alone is already going to be incredibly frustrating to prepare for as Pelipper and Swampert are already incredibly strong Rain pivots to enable Archaludon, who in turn mauls all of the "typical" Rain checks such as Slowbro and Tangrowth. Mons such as Hippowdon and Tyranitar just simply do not win against it head on either as Dragonium Archaludon can wipe Hippowdon off the map at +1, while Tyranitar gets Body Pressed or Aura Sphered to also lose long term. Common bulky grass types like Mega Venusaur and Hydrapple have major flaws into rain such as Venusaur having its recovery stunted due to the weather and Hydrapple hating the Dragon typing more than ever because of Archaludon and Mega Swampert's Ice Punch coverage. You mention Rillaboom sweeping rain bar the Flying and Dragon types but threats in question are so insanely powerful under rain that Rillaboom can't be a long term answer either. Rain guys such as Salamence, Galarian Moltres, and again Archaludon forces both sides to engage in very uninteractive trade wars. If none of the rain checks can actually shut it down fully, that means you most likely need to overcompensate via check stacking.
Consistently checking this core alone puts unnecessary strain on the metagame as a whole. Throwing in the other 3 team slots into the mix for yet another Rain Wallbreaker such as Keldeo, Barraskewda, Kingdra, Basculegion-F, or Hurricane spamming, or whatever flexible utility Rain needs to be powerful just makes me wonder why I'm bothering to bend overbackwards trying to check rain and its multitude of variants when the tier was fine before it.
Damp Rock ban allows people to run out the clock faster but it doesn't make rain balanced. All the checks are still shaky, the constrain still remains. Rock bans are primarily focused on by tiers who use manual setters.