If you use Magnemite as Chinchou yes, Chinchou does it better. Otherwise, Magnemite is a much different Pokemon. First of all, it can endlessly switch into Spritzee something which both Chinchou and Pawniard cannot do (btw Pawniard is usually 2HKOed with hazards or non Eviolite). Second, I would go out on a limb and say it's likely the best check in the metagame. It's the only thing that checks Carvanha and Tirtouga through TWO flinches (assuming Tirtouga's Sturdy was broken by something else). It can dent all of its switch ins (does ~40 to Restalk Chinchou) and if they aren't immune to Volt Switch, they get bounced off, meaning Magnemite isn't only a good check but it's an amazing pivot. The only thing holding Magnemite back is the fact that Stealth Rock breaks Sturdy, but that's something that good players know happens and can easily play around it. Did you know you can switch Magnemite into Misdreavus Shadow Ball and restore yourself to full HP with Berry Juice? Well you do know. Should stay A forsure.
Magnemite is absolutely very different than Chinchou, and the best switch in to Spritzee, but then again that's not a huge niche considering that most Spritzee run only one attacking move.
But I have to ask what ungodly set you're running on Magnemite if you have one that checks both Magnemite and offensive Tirtouga (which is the one you'd need a check for). If any hazards are up, it can't check either reliably on its standard Berry Juice set or even the scarf set.
196+ Atk Life Orb Carvanha Waterfall vs. 0 HP / 0 Def Magnemite: 17-21 (89.4 - 110.5%) -- 62.5% chance to OHKO after Stealth Rock
+2 212 Atk Tirtouga Waterfall vs. 0 HP / 0 Def Magnemite: 22-27 (115.7 - 142.1%) -- guaranteed OHKO
To check them, it has to be switching in on them, so Jolly Tirtouga outspeeds as +2, and at +1 Carvanha also outspeeds and OHKOs more often than not. While Magnemite does OHKO both with either Volt Switch or Thunderbolt, it still can't take the hit.
The Misdreavus point is a bizarre one as well, since I have no idea what you'd accomplish with that. While you do activate Berry Juice, Misdreavus still outspeeds and 2HKOs, while Magnemite can't OHKO. You're either forced to try and recycle stall or be forced out, having no berry juice and sturdy still being broken by rocks next time you switch in. No benefit is gained whatsoever.
I'm not opposed to Magnemite staying in A, but it does require team support to remove rocks/spikes, which is a point against it considering its lack of recovery outside of berry juice and low speed without a scarf.
























