Okay, updates on Mega Diancie and Mega Metagross.
Mega Diancie gains a huge boost to Speed, but also gains boosts to Attack and Sp. Attack at the cost of losing a bit of Defense and Sp. Defense. It of course has the aforementioned Magic Bounce ability. Kinda interesting how it goes from something slow and bulky to a speedy attacker, can't wait to see how that will have an impact on it competitively.
As for Mega Metagross, it gains boosts in all of its stats, but especially Speed. It's also been confirmed to have the Tough Claws ability. Pretty nice to see boosts in all of the stats there, and while I do think Tough Claws has been a bit overused on Megas, given the ability was already used on two other Megas already I do think it can help Metagross a lot given how much it suffered in the generation shift.
Thoughts?
I feel that Agiligross could make a comeback this gen. Mega Ampharos got away with Agility, despite the reduced Speed, so why not Metagross (assuming its Speed decreased or remained relatively the same)? The power boost to its contact moves is pretty much appreciated, considering that its STABs, Meteor Mash and Zen Headbutt, are also contact moves. The elemental punches, Hammer Arm and Pursuit also got buffed up:
-Agility
-Meteor Mash
-Earthquake/Zen Headbutt
-Ice Punch/Thunder Punch/Zen Headbutt
Nature: Adamant/Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Metagrossite (if that's the name of Metagross' Mega Stone)
Ability: Clear Body
Edit: Okay, just realized that Megagross' Speed is buffed significantly, so it won't need Agility, though it's still useful for outspeeding other Scarfers. All-out attacking sets are easier to use with the increased Speed, as well as Stealth Rock:
-Stealth Rock
-Meteor Mash
-Earthquake/Zen Headbutt
-Bullet Punch/Ice Punch/Zen Headbutt
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Metagrossite
Ability: Clear Body
or
-Meteor Mash
-Zen Headbutt
-Earthquake
-Ice Punch/Pursuit
Nature: Jolly
EVs: 4 HP/252 Atk/252 Spe
Item: Metagrossite
Ability: Clear Body
Oh and mixed Rock Polish Mega Diancie seems tempting. The loss of bulk kinda sucks with those common weaknesses, though.:
-Rock Polish
-Moonblast
-Diamond Storm
-Hidden Power (Fire/Ground)
Nature: Hasty/Naive/Rash/Mild
EVs: 4 Atk/252 SAtk/252 Spe
Item: Diancite (assuming that's the name of the Mega Stone)