“6th gen Pokemon is too easy!  I played through the game and I was 10 levels over everyone the whole time!”

Turn off your Exp. Share, it fixes that.

“6th gen didn’t add enough!  There was only like, 7 new Pokemon added!”

6th gen added a new type, and though it only added 71 new species, only one of which being related to a previous line, it also added 47 Mega Evolutions for an effective total of 118, more than Johto or Sinnoh.

“All the new Pokemon are stupid, only the originals are good!”

And there’s the Genwunner revealed.  

I really hope these same arguments don’t come up as much in Gen 7, but I know they will.