>>19172077Breloom's biggest threats are Skarmory, Dragonite, and as of gen 6, Togekiss.
The first speed ties, so 4+ EVs outspeeds uninvested Skarmories but even a Swords Dance Drain Punch wont do enough damage to make up for the Brave Bird or even Air Slash.
The other two are faster, so only Jolly invested Breloom can beat them and Dragonite can raise its speed anyway, and Togekiss not only has Thunderwave, but I dont think you'll get fast enough with nature alone to outspeed even the rare Modest togekiss.
tl;dr, Outspeeding your biggest threats doesnt make them any less stupid to stay in on.