Hattrene is not switching into any of the rockers, and it cant consistently keep them off as one bad read is game over as most rockers can threaten it for up to 50+%. Skarmory is a spiker that gets shut down by hattrene but who are its most common partners.... lets see....
| Chansey 42.749% |
| Slowking 34.702% |
| Quagsire 22.024% |
| Mienshao 16.014% |
| Excadrill 14.874% |
These pokemon can absolutely wreck hattrene and abuse it as you can easily double switch to these pokemon as the switch is obvious. CM sets have a hard time to get going with slowking teleport into smth like LO mienshao, excadrill, nihilego, nidoking, conkeldurr are all pokemon that just wreck it, and its not strong to start off without a few boosts. The new set seems to be HW three attacks... which is we will see how it is it does not seem like a B+ pokemon, it seems as viable as entei and is the definition of a B pokemon which is can be good and has its flaws, or needs more support than the A tiers which it qualifies for
What you are missing in this scenario is that you don't run Hatterene to deal with Rockers. One of it's most common pairings is to run it as support to Exacdrill which is pretty decent at keeping Stealth Rock off but can't keep Spikes off at all. That's practically part of Hatt's role, alongside being a decent check to some stuff like Fighters + Hyd.
I think you oversell the matchup versus stuff like Conk for CM In particular here,
+1 0 SpA Hatterene Draining Kiss vs. 0 HP / 4 SpD Conkeldurr: 300-354 (85.4 - 100.8%) -- 6.3% chance to OHKO
252+ Atk Guts Conkeldurr Facade (140 BP) vs. 252 HP / 244+ Def Hatterene: 198-234 (62.2 - 73.5%) -- guaranteed 2HKO after Leftovers recovery
The draining kiss here would literally heal you more than conk damaged you in this scenario too (70.7 - 82.7% recovered). This is obviously pretty similar for the Shao example where all it could do is potentially Pjab poison you while you heal off all damage + more since that only does like 50-60%.
Calm Mind sets in general aren't quite as invalid as you make out imo, while they will fail into matchups like Wish Jirachi or fat teleporter + nidoking, they are perfectly capable of breaking examples like Conk/Shao that you listed and healing off all damage, while checks like Excadrill and Scarf Jirachi get very easily worn down by hazards + helmets over a longer game, and aegislash will usually lose the 1v1, though how much chip it needs first does depends on its spread in question.
Personally I think you are really underselling Hatterene here with your original post,
I still believe it has a niche in B/B-, it is way harder to stop once it gets going due to magic bounce, and abuses skarmory like no tomorrow. BUt even that is still not worth the slot.....
It's pretty clearly got a defined niche that makes it very worth a slot on certain teams: handle skarmory for spin exca teams that don't deal with the free spikes that exca gives too well. Other additions like the 3 attacks + healing wish set only further add to its value by making it an actual offensive presence when not facing slowking or chansey, backing off its solid SpA while making it a fantastic offensive support to teammates.
Whether or not it deserves to stay in its rank is another matter but you have frequently misssold Hatt's niche or its matchups in these two posts imo.