MegaLucario seems to have an unchanged move-set besides his aura maxed out during his FS, making him stronger & faster movement.
MegaCharizardX has no info on it at all so this is where the speculation starts, with
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adding in the missing pieces.
Atm
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has 2 Dark-esqe moves confirmed, one technically being Shadow Sneak but not in the evil-esque darkness type of move like
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's Nosferatu. Rather it's a feint kind of attack more on the side of emphasizing his go-to Ninja style of fighting in the same sense
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doesn't use Steel-based moves but manifests its own aura into a weapon, Aura being his most iconic mechanic.
Taking this speculation of
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literally fitting his appearance of a Water Ninja Frog improvising with moves that are in fact dark-type moves from the game, Sakurai & the development team are taking note of them from the games & implementing them similarly to Super Smash Bros.. And his FS called out as Night Slash by fans with a dark-theme with the full shining moon in the dark-sky BG, it's no surprise this is another Dark-type move promoting
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's Dual 2nd type.
This said
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's Flare Blitz mechanically is similar to how the move is done in the games, adding in a recoil drawback when the move hits on contact. Nothing more can support Charizard for speculation but if it's anything like
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& his FS notion, I wouldn't be surprised in the slightest for MegaCharizardX to get an altered move-set highlighting on some Dragon-esque attacks, because MegaCharizardX is a fire-breathing dragon. The most interesting point I find about the new
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is the lack of information we have about anything pointing toward his Dual-type Flying in any form of attack using his wings or physically using wind as an element promoting that. This
wiki of confirmed information shows none of his past Brawl attacks involving his wings in his Sm4sh move-set. U-tilt, U-smash, & technically his UpB Fly were all wing/flying moves, which gets me thinking ahead of myself that
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may have gotten changes to his move-set to promote the idea of Fire/Dragon dual type MegaCharizardX.
What does this have to do with Sceptile, or perhaps, any grass starter you ask? Simple, they're taking the pokemon types even more seriously, making
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the most suitable example, Improvised him the way Sakurai did, it worked out rather well. It's important when I say
FIRE Breathing Dragon &
WATER Ninja Frog, because now with the heavy pushing they did so far with both of them, including the Grass-esque moves already making an appearance, how can we deny that we'll get a
GRASS Slashing Gecko, let alone any
GRASS type pokemon? With how it may go for MegaCharizardX in my speculation, the same can go for MegaSceptile being the FS if it went that far.