Oh my bad it doesn't OHKO. Still think you're using some unfavorable calcs below. I don't know what set is standard on arch by now but surely im not the only one using impish and instead relying on body press rathan than special attacks- and dragon tailing away anything that can take body press well to add up hazard damage? Because with zero defense ran I'm thinking you would be using like.. electro shot instead? On the same token wouldn't people run jolly urshifu in this meta?HUH?
+3 252 Def Archaludon Body Press vs. 0 HP / 4 Def Urshifu-Rapid-Strike: 217-256 (63.6 - 75%) -- guaranteed 2HKO
252+ Atk Urshifu-Rapid-Strike Close Combat vs. 200 HP / 0 Def Archaludon: 344-408 (92.7 - 109.9%) -- 56.3% chance to OHKO: Roll to kill with no boosts
+2 252+ Atk Punching Glove Urshifu-Rapid-Strike Surging Strikes (3 hits) vs. 200 HP / 0 Def Stamina Archaludon on a critical hit: 130-156 (35 - 42%) -- approx. 3HKO
It switches in, takes 35%.
+2 252+ Atk Urshifu-Rapid-Strike Close Combat vs. +3 200 HP / 0 Def Archaludon: 276-326 (74.3 - 87.8%) -- guaranteed 2HKO
WOW, IT KOs EVEN WITH ARCH AT +3+2 252+ Atk Choice Band Urshifu-Rapid-Strike Surging Strikes (3 hits) vs. 252 HP / 252 Def Stamina Archaludon in Rain on a critical hit: 220-260 (57.2 - 67.7%) -- guaranteed 2HKO
The way you're laying out the calcs, the even at +3 one, means you what- hit surgical strikes, take the body press, 70 - 82.6% with impish, while you swords dance, and then a max/max arch at +3 takes from +2 Close Combat 48.9 - 58.3% losing to the next body press.
Archadludon isn't a counter- but it does make urshifu a little hesitant to use its signature move. It's not going to be able to just click swords dance and destroy in this game not with serp thunderclap grassy glide etc.