Tbh this prob one of the stupidest things I ever seen. Just because you use a gimmicky Regice set doesn't mean you deny the proper calcs for the most common and viable set.
I've
been playing Stat Switch, and I have enormous doubts about "common" and even greater doubts about "viable".
More generally, Regirock and Regice
really aren't as hard hitting as they look. Regirock's best damage output is about equivalent,
before IVs and EVs are counted, to a STAB 90 BP move off a Pokemon of about 130 Special Attack -so Breloom using Energy Ball, say.
After IVs and EVs it's more like a Pokemon with 118 Special Attack -and there's plenty of Pokemon with that much. In fact, Regirock is essentially outclassed by Carbink in every area, with the Speed tiers working out so that only, out of Stat Switch-OU-legal Pokemon the Regis themselves, Steelix (Almost certainly being used as a Mega, if at all), Aggron (Almost certainly being used as a Mega), Mega Slowbro, Mega Garchomp, Bastiodon, Mega Ampharos, Mega Banette, Mega Tyranitar, Snorlax, and then tied with Carbink are Diancie (Bad Carbink in all regards), Doublade, Probopass, Registeel, and Mega Swampert are all the Pokemon that out-speed Carbink or speed-tie it while being outsped by Regirock.
Note that a
lot of these Pokemon are Megas, and some of the non-Megas aren't even viable. There's
really no reason to use Regirock when Carbink is almost always going to hit harder, outrun the same stuff, and tank hits better. Carbink can even run Scarf if it wants (That makes no sense on Regirock) and will
still have comparable damage output to Life Orb Regirock while outspeeding it and things it doesn't outspeed!
And it has Sturdy!
And it's less predictable! (Physical Carbink is plausible, and to a lesser extent support Carbink. Regirock is a straight attacker who
maybe sets Stealth Rock)
Regice is less bad off -as far as I'm aware there's no Carbink to its Regirock to
horribly invalidate it- but Pokemon with lower offenses still do similar or better damage. Keldeo's Close Combat is about equivalent to Regice's Ice Punch, Keldeo is still respectably fast, it gets Aqua Jet, it has better bulk (More HP with 90 in its defenses, so even on Regice's stronger stat Keldeo is about equivalent), it has a more useful ability (Justified is now relevant!) and can even properly set up! (Swords Dance) Any STAB Earthquaker with 135~ Attack does similar damage to Regice's Ice Punch after investment, not even getting into all the STAB Close Combats, STAB Flare Blitzes, and so on that lower that Attack requirement
still further to equal Regice.
Regice and Regirock (Actually, not really Regirock because Carbink) definitely have
uses, but they are also deeply flawed, and not nearly as impressive as they look on paper. In fact, playing Stat Switch has provided substantial illumination for me as to why the Regis are so goddamn awful in Standard -because their movepool is just not very good at much of anything. (And yeah in Stat Switch they're using the opposite attacking stat for which their movepool is particularly bad, but they just lack good tools in general)