Firstly, GameFreak is the group responsible for Mega Evolution (not to mention everything else you'll find in a Pokémon game), and secondly, Mega Evolution is a completely necessary game mechanic simultaneously making fans' favorite weakmons usable and doing a damn good job of both maintaining and expanding the fanbase with glorious, melt-your-face fanservice such as Mega Mewtwo Y and Mega Charizard X.
As Nintendo is associated with Game Freak, it's very easy to confuse the two often- you know what I meant; same difference.
"Mega Evolution is a completely necessary mechanic"- Umm, can you explain to me how it is NECESSARY when we've gone 5 Generations in 15 Years without it?
"...making fan favorite weakmons usable..."- Name one Mega Evolution that was considered Weak before, because last time I checked, each of them, including Ampharos, were all strong Pokemon in their respective Tiers, while Pokemon such as Farfetch'd or Dunsparce that need one were left in the dust.
And about the "glorious melt-your-face" bullshit, I find it funny how you confirm my point in using the word "fanservice" after all of that. To me, that's just Nintendo- oh, excuse me- Game Freak sucking Generation Wunners dick in fear of losing a already solid Fanbase, which, in fact, generated MIXED feelings about X and Y due to the distortion of their favorite Pokemon's image.
The fact that you use Charizard as an example is very funny, as that yet again proves my point- Mega Evolution on an already Top-Tier Pokemon such as Charizard (SR's can be dealt with) is completely unnecessary, amd is implemented for the sole reason of "glorious melt-your-face" or whatever you said
Fanservice