Except there... Is a reason to not like Empoleon :/
Unlike Gardevoir, it doesn't speed up your set up. At all. This means you are behind in speed.
Unlike Gardevoir, it doesn't slow the opponent's set up (No, sniping does not prevent them from using Claydol's powers). This means you can't recover from being behind in speed.
Unlike Magmortar, it will never OHKO any stage 2 pokemon, and can't OHKO several commonly played stage 1s, meaning you are behind in power.
Unlike Typholosion, you can't remove energies with Empoleon's attacks, meaning you can't recover from being behind in power.
Unlike Typholosion or Blaziken, it can't make energy hit the table fast. This means you will be behind in power or unable to recover should they knock out your Empoleon.
It is durable though, that's a conceded point. Gardevoir has a heck of a time taking it out, and Gallade's being seen less and less as people realize how superior Gardevoir is. In fact, Empoleon beats Garde in a one on one match (70 damage twice KOs Garde, where as 60 twice doesn't KO Empoleon. It's even worse when you consider how Garde usually uses DRE). That being said, Empoleon takes a bit to build up, as most damage spreaders would. Although Gardevoir specifically can't two hit KO Empoleon, Gardevoir usually will have a back up hitter on the bench ready to attack after the first falls. What does Empoleon typically have to act as back up...?