For Assault Vest Magearna, we have things like this
Remember that Fleur Cannon still has a decent amount of power behind it, so using it does not forfeit as much momentum as one might expect it to, especially for maximum Special Attack variants.
Assault Vest Magearna never runs maximum special attack, and Maximum Special Attack Assault Vest variants are never mentioned again during the entirety of the analysis.
VoltTurn teammates are appreciated because Magearna has Volt Switch to form VoltTurn cores. Ash-Greninja, Landorus-T, and Tapu Koko are good examples
U-Turn isn't even mentioned in other options in the Ash-Greninja analysis, this should probably just be changed to Choice Scarf Greninja
Also I thinks its a crime, that its never mentioned that AV Magearna can get worn down across match after repeated hammering, which is can lead to pokemon like Tapu Lele being able to break it, which I beleive is the primary reason AV Magearna is mostly used on BO as the playstyle appreciates pivots like Magearna that can provide stops to pokemon without wasting momentum thanks to Volt Switch. Oh, and it should also be mentioned that Magearna fits best on Bulky Offence.
Now onto Shift Gear
A Shift Gear set trades Trick Room sets' bulk, power, and favorable matchup against faster Choice Scarf users such as Keldeo and Infernape for more reliability in completing a successful sweep.
So there is two problems with this. First Trick Room is mentioned last in the analysis, so this seems to be out of chronological order, which can confuse readers. Second, Infernape is no longer viable and should be removed, and Keldeo can only revenge Magearna at 60% health and only on a high roll, so I'm not sure how relevant mentioning it is.
Shift Gear boosts Magearna's Speed by two stages, allowing it to outpace everything up to Choice Scarf Nihilego. The Attack boost does not matter because Magearna is a special attacker
This isn't really a mistake, but this mention feels so abrupt, and probably could be worded better
Twinkle Tackle is a great nuke capable of blowing away Clefable, Mew, and Zapdos, without a boost. Ice Beam can be used in place of Fleur Cannon which provides Magearna with wider coverage, nailing Pokemon such as Zapdos and Landorus-T.
Twinkle Tackle can hit all the pokemon above mentioned, and just as hard as Ice Beam. I think in place of Zapdos should be Tapu Bulu, and it should be mentioned that the reason to use Ice Beam is so that you have unresisted BoltBeam coverage, while not having to waste a Z-move on those pokemon. Similarly, the phrase "without a boost" can be confusing, because Magearna isn't boosting its special attack and is faster than all the mons listed, so that phrase should probably be deleted.
Fightinium Z is a great alternative, since it capitalizes on Shift Gear's versatility, allowing Magearna to break healthy Steel-types
This one bugs me, because it should be on the actual set, because it gets consistently mentioned throughout the rest of the analysis.
It isn't a mistake though
Shift Gear sets can be used as mid-game breakers because of their use of Speed investment and unlimited turns for sweeping, unlike Trick Room.
Out of chronological order again
Double Dance Magearna
Alolan Ninetales deserves a special mention because of the incredible support it provides in Aurora Veil, which gives Magearna a much easier time setting up and makes it an even deadlier threat.
Not a mistake, but dual screens Tapu Koko should be mentioned here as well, due to being similar, but I can see why its not mentioned
OTR Magearna
Aura Sphere is a 100% accurate Fighting-type move, but it requires its targets such as Ferrothorn and Magnezone to be at a low amount of health before it can KO them.
This one annoys me, because this one is in the moves section but isn't mentioned in the set, unlike Fightinium on Shift Gear which was also not on the set but was on Set Details instead. The analysis needs to make up its mind on where these type of things get mentioned
but it will find itself useless in certain matches depending on its moveset, as it's walled by Pokemon such as Roost Volcarona, Celesteela, and Mega Scizor
Similar to Ash-Greninja and U-Turn, Roost is never mentioned ever in Volcarona's analysis
Other Options
None I can spot
Checks And Counters
Jirachi can effectively defeat every variant of Magearna outside of the rare Never-Ending Nightmare set.
Why does Never Ending bother getting a mention if it isn't even mentioned in Other Options. Not really a mistake though
Fire-types:
Long Story short, M-Camel and Charizard X should be mentioned in this section
Ground-types:
Similarly, Mamoswine deserves a mention here, since its now OU.