There's just no saving Flareon. I'm sorry, but it's just too bad.
"Saving" Flareon doesn't mean it has to outclass Arcanine, Darmanitan, Infernape, and other physical fire types. Even something like Entei is RU (aka, not that strong), yet most players are content with it. "Saving" Flareon would just be giving it a purpose, even if it's outclassed, such that it's not by far the worst eeveelution.
In the Dream World, the 3 original eeveelutions all got abilities related to status effects: Vaporeon with Hydration to cure status; Jolteon with Quick Feet to increase speed when statused; and Flareon with Guts to increase attack when statused. Given that Jolteon is already one of the fastest pokemon in the game, Quick Feet isn't really the most useful ability.
But what if Flareon got
Quick Feet instead? The 50% boost would allow her to outspeed Base 115 speed pokemon. (Faster than things like Starmie, Gengar, Latios, etc.) Considering that Flareon already has a base attack equal to Scizor, this along with moveset like Flare Blitz, Crunch, Superpower and Facade would make Flareon a very apt revenge killer.
(Flare Blitz could be saved as a last resort, because of low HP. Facade still hits hard at 140 base power. Ursaring has Quick Feet despite having just as bad speed as Flareon, so this wouldn't be unusual for Flareon to have)
edit: this would not make flareon any better, but i think it would be cute if flareon could use cotton guard, lol bye