There is no conformation or even anything that hints towards Clemont catching that Luxio only that he befriended it as a Shinx when he was younger. Don't jump the gun quite yet guys, though I agree Mega Luxray would be awesome.
I'd also like to see a Mega Boufallant with Fur Coat since Bouf's dex entries state that its fro absorbs damage. Honestly I think the only reason it didn't get Fur Coat in XY is cause it already had 2 normal abilities and a Hidden Abillity. Though i am surprised they didn't change its HA like they did for Venipede. Soundproof doesn't really make sense unless that afro is so thick it absorbs sound.
Edit. Ignore the top part seen the pic that seems to show Luxio will be captured.
The afro covers its ears so it can't hear...If it did go mega and got fur coat, I'd want it to looks like a yak...
I'm sure GF will do something cool with Mega Flygon to differentiate it from Garchomp. Just see the differences between Zygarde and Garchomp.
The general offensive set for chomp and zygarde don't really play very differently though...they both use a boosting moves (d-dance/ coil vs SD), 2 physical STABs (outrage and EQ) and one coverage move (E-speed/ stone edge vs fire fang/ stone edge/ poison jab/ iron head)...the only differences is that one is more defensive where it can achieve boosts that help it last longer while the other is faster and can deal lots of immediate damage without the need to set up...along with certain niche moves such as zygarde's E-speed priority vs. chomp's poison jab/ iron head fairy coverage...otherwise, they play very similarly with zygarde being significantly less popular due to its lack of immediate power while still retaining the same 4X ice weakness that chomp has while unable to abuse scarf like chomp can....and although defensive zygarde with coil is possible, it's just an ice beam waiting to happen with zygarde's subpar speed...HOWEVER, I'm confident that zygarde will get a buff pretty soon (mega evo or alternate forms) and along with its unreleased special thousand arrows move, it will become significantly better than garchomp and most likely will become Ubers in the future...
For flygon, it's essentially a mediocre garchomp with a slightly different play style...its stats are offensively-oriented with pretty good speed and decent attack that are completely overshadowed by chomp's stats...all flygon really has over chomp is a slightly stronger coverage move in the form of fire punch and the very niche u-turn, which makes it a great scarf/ band scout that is much better than noivern for the job, which is a decent trade off for its lack of boosting attacks save the mediocre hone claws...if it does get a mega that still keeps dragon/ ground, it's going to need enough speed to outspeed garchomp to even be considered in OU...since it has no item access, stuff it will normally outspeed with scarf (notably greninja) will no longer be outsped simply making it a worse garchomp...IN UU, there is a possibility for it to shine but choice scarf flygon is the norm there...the only other way for flygon to be unique while still retaining dragon/ ground might be making it special rather than physical...but landorus already stomps all over that once again usurping flygon's OU potential...
That's why I think in order for flygon to be a force in OU is for it to change its type upon mega-evolving to make it completely different from chomp...as everyone has already suggested, myself included, changing its typing to bug/dragon will do just that...this type change doesn't just aesthetically and logically make sense but it also centralizes around flygon being that ideal scout-dragon giving STAB to its u-turns...this typing will eliminate its 4X ice weakness as well making it harder to OHKO...a trade off will be the obvious rocks damage and more weaknesses but it does get roost to compensate and has great type coverage in its movepool...as for ability, tinted lens is great allowing it to get neutral or SE STAB U-turns off on everything and not getting completely walled by fairies...as for stats, give it 20 speed to outspeed chomp, 30 attack to equal chomp, and either 25 in both defenses or 25 in SA and 25 in defense with SD untouched since flygon has a pretty decent special move pool to work with...
BUT, Smogon tiers are nothing official therefore making my reasoning lose weight but either way, a bug/ dragon would still be pretty cool...