As said on Serebii, codes for Europe are expected tomorrow.
I would say Quiet makes for the best 'alternative' set if you aren't going for Modest or Timid. Unless you want to try bulky/support, in which case... I guess Calm works.
Minor nitpick, but Calm is the +SpD -Atk nature. Careful is -SpA (assuming you wanted a -Atk nature)
Source? Never been able to synchro for gift Pokemon before.
I know I did about 10-20 SRs with a Modest Sync before keeping a HP Fire Magearna and all were Modest (similar to cosplay Pikachu and the gift Lati@s during ORAS's story).
Have similar reasoning for a slightly different question:
Eh, Fleur still hits like a truck and the ability does let you potentially sweep late-game (even on bulky sets every now and then) or at least lessen Fleur's drop if you have to attack again--a la Latios needing to attack after a Draco.
Honestly it was smart of them to give it 65 speed.
I personally like the slower Volt Switch in that situation, but if you're using TBolt that's the best option. Soul Heart actually is slightly better than Moxie since it triggers when your opponent dies to after-turn effects (poison/burn/sand/leech seed/hazards). IMO that makes stuff like Toxapex or Hippowdon pretty nice with Magearna since they can set up hazards (or sand in Hippo's case) or status things to trigger Soul Heart.
70 Base speed isn't really high enough that you can't call it a Slow Volt Switch. The most common Volt Switch user in the previous gen was 86
First, I am not even sure how Modest VS Hasty is a contest? Why on earth would you want to decrease her defense stat, when one of her strengths is actually being able to take hits. So I will assume you meant something else.
Hasty wasn't a typo, I wrote up a mixed Shift Gear set on page 1 and in the Z moves thread, consisting of Fairium-Z, Fleur Cannon, Aura Sphere, Explosion and Shift Gear with a Hasty Nature. It needs the +Speed nature to outspeed Scarfchomp while I'd regard SpDef as more important to somewhat wall Psychic spam since there's no weakness to any type of priority. But regarding that set; I don't know if I want my ingame Magearna niche, since once the meta settles, I expect HO to die down, and the more defensive the teams are, the less late game cleaner Magearna works.
Moxie is a great ability. How can you call something that makes sweeping easier a bad ability? It was a good ability on Mence in Gen V, as well as DD Gyara in early BW. Soul Heart is an amazing ability for Magearna, which relies on weaker BP coverage moves to nab KOs, meaning that getting an extra +1 in SpA can mean the difference between a sweep or not. It also gives stuff like the AV set more of an intimidation factor, since you can't just sack something and bring in a check as easily.
Shift Gear and Gyro Ball in one set is quite a questionable choice so nope. Apart from this, Gyro ball requires really slow speed to be useful, the only things that actually use it succesfully are ferrothorn and bronzong (and I guess gyroball aegislash aegislash, but this is specifically vs boosted xerneas) which have much lower speed and dont mind minimizing it. While magearna can live without speed investment, it still likes outspeeding slower defensive pokemon.
