Does Solid Rock ensure some key survivals that Rhydon falls to?
I'm not belittling Rhyperior, but his traits might not be enough to propel him into the top 10 or so of UU. But lets wait till he actually comes into UU before discussing this.
It will still need to run from all the special attacking Water and Grass types in the tier just like Rhydon does, but the stat increase and Solid Rock would make Rhyperior a hell of a lot more resilient to physical attacks:
252+ LO Honchkrow Night Slash vs 164/0
Rhydon:
34.44 - 40.82%
252+ LO Honchkrow SuperPower vs 164/0
Rhydon:
79.08 - 93.37%
Average damage roll of Night Slash + SuperPower vs
Rhydon:
123.2%
Average damage roll of SuperPower + SuperPower vs
Rhydon:
143.3%
252+ LO Honchkrow Night Slash vs 164/0
Rhyperior:
30.83 - 36.65%
252+ LO Honchkrow SuperPower vs 164/0 (Solid Rock)
Rhyperior:
52.67 - 62.14%
Average damage roll of Night Slash + SuperPower vs
Rhyperior:
90.5%
Average damage roll of SuperPower + SuperPower vs
Rhyperior:
94.8%
As you can see, with this spread (164 HP / 252+ Atk / 92 Spe), Rhyperior can come in on any of Honchkrow's attacks and kill it or force it out, something that Rhydon could never hope to have done, while still outspeeding all the base 50s (Chansey, Donphan, Regirock, Registeel, Azumarill, Hariyama, etc) with its 92 Spe EVs.
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Rhyperior's damage output isn't too much higher than Rhydon's, but can get some crucial 2HKOs Rhydon missed out on:
CB Rhydon Earthquake vs 252/252+ Donphan:
44.53% - 52.60%
(18.47% chance to 2HKO with SR and Leftovers)
CB Rhyperior Earthquake vs 252/252+ Donphan:
46.88% - 55.47%
(68.97% chance to 2HKO with SR and Leftovers)
The odds are no longer in the Donphan user's favour. The other thing is that Rhyperior doesn't have to fear Donphan's Earthquake nearly as much as Rhydon did:
0 Atk Donphan Earthquake vs 164/0
Rhydon:
55.61 - 65.82%
(guaranteed 2HKO if Donphan outspeeds (runs more than 16 Spe EVs))
0 Atk Donphan Earthquake vs 164/0
Rhyperior:
37.14 - 43.69%
(comfortable survival if Donphan outspeeds)
So in any case, Rhyperior is guaranteed to beat any Donphan switching into it, while Rhydon has a slim chance at best, and Rhyperior can always switch into SR and survive any two of Honchkrow's attacks, while Rhydon would always be taken out.
Pointless theorymon so much fun :) - I think Rhyperior is staying quite stably in OU for the near future at least.