To answer I got a detailed list I will summarize in a very little sentences. Heavy is rally slow which makes flare guns impossible to match with because they can cover long distances. And if the pyro is sneaky enough, kill the heavy easily when they least expect it. Yeah sure pyro is out ranged by the sniper, up close, if the sniper don’t have bushwacka and jarate and if you are unpredictable, he is an easy kill. Every class can dominate the same class… that’s it. Why did you even put spy up on there, pyro is the main counter for spy. Scout has low health and if you hit enough flare, he little punk turns into a crisp. To the engi, you either catch him off guard with all his buildings destroyed or airblast his level 3 sentry’s rockets straight back at him.