I'd say if you want to run Magnezone with Analytical, you have to acknowledge that Magnezone has tons of common weaknesses (fire+fighting+ground). Analytical is basically saying "Okay you can have the effect of a life orb on your attacks as long as you don't outspeed anything". If you're going to run Analytical, I'd say screw choice specs. Your opponent will predict an electric attack (because who uses flash cannon? and if you lock yourself into it, it'll be so easy to wall). If they switch into a ground type and you volt switch that turn, you're fucked, as well.
I parten this thing with Gyarados all the time, and why wouldnt I switch in all of these scenario's
If you're going to run Magnezone w/ Analytical you should probably run Life Orb over specs.
I do agree with this a little, its basicly for preference of which you prefer.
Voltswitch / Thunderbolt
Tri Attack (it's better than flash cannon for the status chance and is basically resisted by the same threats anyway)
HP Something (Fire or Ground)
Magnet Rise / Substitute (or explosion)
Volt Switch (for Safe Switch ins, and Scouting)/ Flash Cannon (Because it gets STAB, making it stronger than Tri-Attack + comes with a small chance to lower Sp. Defense.)/ Thunderbolt (Main STAB)/ Hidden Power[Fire] for Ferrothorn.
Substitute is a good idea I do agree.
The first 3 attacks are for coverage, the last is for predicting a switch. Substitute is better overall but Magnet Rise will deal with hearty EQers like Dusknoir or TTar or Gliscor (but TTar and Dusknoir can always carry fire punch/fire blast so it doesn't help too much).
Dusknoir? Most people use Dusclops now, which dont use Earthquake. Gliscor is covered by Gyarados and Ttar can cause problems, But I can catch him on the Switch and use Flash Cannon (Yes , Flash Cannon). Max Hp and SpD Ttar takes 54% minimum from Flash Cannon. And if I invest 12 Spe Evs into Mzone I outspeed The Ttar I just said.
Since Analytic encourages you to take hits, I'd say try testing evioilite + magneton vs magnezone + life orb and see which one works better. But in either case, Magnezone lacks a diverse enough movepool to make use of analytic and is simply too vulnerable to the common offensive attacks and can be easily walled by SpD walls unless you run explosion (and an analytic explosion... no idea if that's gonna work or not). It's not really a strong ability for Magnezone.
Magneton has less Hitpoints than Magnezone (base 50, base 70) and Magnezone provides more SpA.
Finally, why are you putting 4 EV in speed? I understand you want Magnezone to hit things, but honestly you shouldn't be boosting its speed at all. Otherwise you're just wasting your ability. You should run a minus speed nature and put 0 EV/IV in speed, especially if you choose to run explosion.
It was filler option? Honestly what Pokemon has exactly 1 speed point less than Magnezone?