I don't see what's the problem with Pyroar. Sure, nobody likes clunking up their deck with something just for a single matchup, but what Pyroar does is encourage more play for Evolutions, which is great because Evolutions shouldn't be so outclassed by Basics. The "fact" that "it can not be damaged by 90 percent of the stuff people run" is due to improper game balance.
Most decks have some sort of counter/check/answer to Pyroar, and they have a lot of decent choices for them. Pyroar can still win against them by Lysandre up their counters, but it isn't like they don't have a chance.
-Yveltal-EX decks can use Raichu XY, Garbodor LTR, and Zoroak LTR. These decks probably would've ran some of these cards even if Pyroar was never released.
-Virizion/Genesect decks have G Booster, and they can use Raichu XY or even Abomasnow PLB (don't forget Red Signal to attack around Pyroar). The reason why this matchup is so bad is really just because of Pyroar's typing. Most decks that run Fire Pokemon can beat this deck.
-Plasma decks can run Latias-EX, Glaceon PLF, Umbreon PLF, Flareon PLF, or Froslass PLB. You can also stall with Thundurus-EX's Thunderous Noise attack. This deck has a bad Pyroar matchup, but all decks have bad matchups, and I've seen Plasma win sometimes.
-Aromatisse can use Rayquaza LTR, Giratina-EX, G Booster, Latias-EX, or Mega Kangaskhan (which some of them are entirely built around). If you are using Giratina, Rayquaza, or Latias, you should be fine if they don't have a Druddigon.
-Landorus-EX decks (like the one that WON US Nationals) run Raichu XY and Garbodor LTR, which they have already been running before the release of Flashfire.
-Blastoise has well. . . Blastoise.
-RayBoar has both Emboar LTR and Delphox XY. They can even run the BCR Emboar along with the LTR one if they are that scared of Pyroar.
-Empoleon/Miltank doesn't care about Pyroar.
-Greninja/Miltank probably doesn't care about Pyroar.
-Flareon doesn't care about Pyroar.
-Flygon/Dusknoir/Accelgor doesn't care about Pyroar.
-Fighting decks after the release of Furious Fists will have M Lucario-EX and Machamp FUF.
Pyroar obviously changes things up, but it doesn't stop things in there tracks that easily.