Some comments on Mega Mewtwo X's analysis:
Lum Berry should definitely be added onto OO; it blocks Spore, which is nice, and also heals off Burns and Paralysis from bulky walls that try to cripple you (Giratina, Registeel, No Guards)
I'll abstain from answering this because I'm not really sure about it but don't have a good counterargument
I dont like V-Create on the set. Precipice Blades deals a lot of damage to most of the relevant Pokemon that V-Create hits; LO 252 Precipice Blades already OHKOs 252/252+ Registeel, and there are no other common Steel-types that invest more in physical bulk (besides Mega Aggron but they dont usually run anything that can hurt you significantly) V-Create also takes priority's spot, and I think priority is a heck of a lot more useful. Sucker Punch checks MMY, Ghosts, and Latios easily, while Extreme Speed checks -ates. Draco is questionable as well in my opinion, but at least it checks Giratina, Latios, and RayMega.
V-C is one of Protean MMX's best moves. It's not just for SE coverage (that is useful but it's not the primary goal). Protean V-Create kills tons of things that don't resist it, which can't be said about Precipice. There's a huge difference in base power. For instance,
252+ Atk Life Orb Protean Mega Mewtwo X V-create vs. 248 HP / 252 Def Mega Audino: 376-445 (91.9 - 108.8%) -- 50% chance to OHKO
252+ Atk Life Orb Protean Mega Mewtwo X Precipice Blades vs. 248 HP / 252 Def Mega Audino: 253-298 (61.8 - 72.8%) -- guaranteed 2HKO
252+ Atk Life Orb Protean Mega Mewtwo X V-create vs. 248 HP / 0 Def Arceus: 480-565 (108.3 - 127.5%) -- guaranteed OHKO
252+ Atk Life Orb Protean Mega Mewtwo X Precipice Blades vs. 248 HP / 0 Def Arceus: 320-378 (72.2 - 85.3%) -- guaranteed 2HKO
Also, with V-C, there is no predicting involved, but with Precipice, your opponent might switch into a Flying pokemon, which is bad.
Yes, priority such as Sucker Punch (not as much ESpeed, more on this in a bit) is useful, but Protean MMX really likes its wallbreaking abilities that V-C gives it. Also, Precipice does not allow MMX to hit Flying types. It should not be removed from the analysis. As for Draco, it's incredibly useful against Fur Coat Gira, one of Protean MMX's primary switchins.
As for ESpeed checking -ates, that's what King's Shield is for. After KS, none of the ate users can do significant amounts of damage because MMX is now steel type (and depending on what move they used first turn, they might be -2 atk). ESpeed's primary purpose is for revenging setup sweepers, not beating -ates. The moves on this set are perfectly fine and have been proven to be viable.
Also this is a smaller change but moves should be listed in order of useability, with utility moves at the end, so the set should look like:
No objection here, except keep the old moves obviously.
Move 1: Bolt Strike / Fusion Bolt
Move 2: Precipice Blades / Thousand Arrows
Move 3: V-Create / Sucker Punch / Extreme Speed / Draco Meteor
Move 4: King's Shield
Bolt Strike puts out insane, reliable power, and should be used as a general attacking move as few common Pokemon in the meta resist it. Giratina is a very important resist. Also, Bolt Strike's accuracy leaves a lot to be desired for a general attacking move. PBlades is next because, aside from the Steel-types it hits, Bolt Strike often deals enough damage (252 non-LO OHKOs Mega Diancie and Mega Gengar) Situational coverage moves comes next, with Sucker Punch first because it checks a lot more relevant Pokemon than Extreme Speed (which is not always a necessity because King's Shield lets you shrug off an ESpeed.) Finally, KS, the staple. I basically responded to this above.