Flareon's problems come from 2 main issues.
1) Stat distribution: We know that the Eeveelutions can be viable. Jolteon, Vaporeon and Espeon prove it more, though Umbreon is decent as well. The problem with Flareon is the bizarre stat spread. 130 Att is great, but the other stats just aren't where they should be. 95 SpA is unnecessary with such a high attack stat and low Def and HP, coupled with it's low Spe, decrease it's survivability. Flare Blitz, while a very appealing move, has recoil and Flareon just doesn't have the HP to survive for long. The solution? There isn't one, outside of totally rearranging it's base stats. A spread of 110/130/65/60/65/95 would have been much better. Fast enough to survive, strong enough to do some damage and enough HP to actually be able to use Flare Blitz.
2) Abilities: Flareon gets Flash Fire and Guts. Flash Fire is alright, but very situational. Guts, on the other hand, is normally a great ability to have. The problem here, however, is how it doesn't really work with Flareon. A paralyzed Flareon has it's already low speed cut even more and is essentially dead in the water, since it can't survive much with it's defenses. Being burned would be nice, since Guts negates the attack drop and Will-o-wisp is everywhere, but Flareon can't be burned at all. So now you're forced to rely on poison, meaning you're probably going to have to run a Toxic Orb, which means death will come fairly quickly.
You probably though "movepool" was one of the problem, but honestly it really isn't that bad...anymore. Most Eeveelutions have problems with movepools, and all things considered, Flareon can actually do something with what it can learn. Flare Blitz and Superpower are a nice combination and Facade can make use of Guts quite well. Rounding out the moveset with Flame Charge can help raise that terrible speed, but if it had the stat spread I mentioned earlier, it wouldn't need it.
Too bad it sucks, though. Flareon's cute.
