got reqs so I'm going to post what I think about magneton now since my opinion on it changed a bit. (tl;dr is at bottom if you don't want to read this wall)
Throughout the suspect I used a specs magneton and although it's one of the most powerful special attacking sets NU has seen I wasn't as impressed with it as I thought I would be. This is largely due to how prediction reliant it is; if you predict right something gets 2HKO'd at worst but if you don't you're doing basically 0 damage. Magneton is a lot more manageable than previous banned threats such as typhlosion and heliolisk because it doesn't have an easy spam attack like typhlosion and it can't just easily bop things that can switch in on one move like heliolisk could. Its speed is not very good as well, meaning it is not hard to revenge kill. Choiced magneton can even feel like dead weight in a game if you miss all of your predictions. And unless you're running specs you're not getting around its main counters lanturn, stunfisk, and torterra. Especially with the former two, even if you hit them with your supereffective hidden power it can just switch out and you still can't safely use your stab moves. Eviolite and scarf don't hit the power level that specs does which makes these sets much more manageable in my eyes, at least in terms of defensive cores.
I feel like people kind of overrate its ability to switch in as well. It has good physical bulk for an offensive mon but its special bulk is shitty to say the least. Not to mention that a lot of its resistances don't matter that much when you factor in many mon's coverage moves (yeah magnets will tank kanga, archeops, and tauros' stab moves, but it's not eating the following eq). Even stuff like mawile and vileplume, two mons that magnets comes in basically for free on their stabs, can run stuff like fire fang/blast and hidden power fire, respectively, which are both viable options that hit other targets as well. With this said the list of things magnets can easily come in on becomes like scyther, fletchinder, psychics (primarily uxie, musharna, mesprit), klingklang, cradily, defensive snowflake, and maybe defensive water types like prinplup and mantine. There are other things you can come in on of course, such as regirock, mega audino, and xatu, but you kind of have to watch out for coverage moves such as eq, drain punch, heat wave, and fire blast. All of this goes to say that it isn't completely easy for magneton to pivot around, it is not difficult to prevent magneton from getting free switches.
So in spite of its raw power and good typing, it can be manageable in practice since it has an overrated amount of switchins and it has a hard time breaking through its counters. This said I do think magnets is the best mon in the tier atm, I just don't feel like it's broken.
On the other hand I feel that magneton's main unhealthy characteristic is the degree of centralization it brings to the metagame. On the suspect ladder it felt like 95% of teams carried at least one of torterra, lanturn, and stunfisk. All three of these are good in the tier regardless of magneton's presence. However, magneton forces you to run one of these, carry a shitton of soft checks, or make completely flawless predictions against it-- or your team gets dismantled. Not to mention the usage of otherwise completely useless lures, such as overheat fletchinder and hp ground [insert random mon here]. The metagame, to me, revolves completely around magneton + magneton counters, and this is not healthy. Thus I feel that magneton deserves to be banned.
Tl;dr
-Magneton is not broken. Specs is extremely prediction reliant and other sets carry much less power. Its low speed holds it back and it has an overrated amount of switchins thanks to many mon's coverage options.
-It does, however, overcentralize the metagame to an unhealthy degree, forcing most teams to carry 1 of three mons or risk being destroyed by magneton
-Ban imo