YJ, methinks it's Aquapolis, but w/e.
It does help against the deck's two biggest weaknesses: Metagross and Sceptile. Entei helps do like uber damage to those two guys, and it's convieniant that the deck's two biggest weaknesses are both vulnerable to fire. It really depends on how much you see tho. If there is a lot of Metagross or Sceptile in your age group, go for it. If your main concern is Blaziken, I'm not sure I would. There's virtually no Sceptile or Metagross in my area, and I live on the easternmost east coast, so if you're planning on using Walrein at the ECSC, I wouldn't TeCh the Entei. But if any of your friends will be playing SceptiMuk or Metagross, go for it.